doc: fix rollback in the 4.6-to-5.0 upgrade guide

This commit fixes the rollback procedure in
the 4.6-to-5.0 upgrade guide:
- The "Restore system tables" step is removed.
- The "Restore the configuration file" command
  is fixed.
- The "Gracefully shutdown ScyllaDB" command
  is fixed.

In addition, there are the following updates
to be in sync with the tests:

- The "Backup the configuration file" step is
  extended to include a command to backup
  the packages.
- The Rollback procedure is extended to restore
  the backup packages.
- The Reinstallation section is fixed for RHEL.

Refs https://github.com/scylladb/scylladb/issues/11907

This commit must be backported to branch-5.4, branch-5.2, and branch-5.1

Closes scylladb/scylladb#16155

(cherry picked from commit 1e80bdb440)

docs/upgrade/_common/upgrade-guide-v4-rpm.rst

@@ -58,9 +58,14 @@ When the upgrade is completed on all nodes, remove the snapshot with the ``nodet
 
 Backup the configuration file
 ------------------------------
+
+Back up the ``scylla.yaml`` configuration file and the ScyllaDB packages
+in case you need to rollback the upgrade.
+
 .. code:: sh
 
-   sudo cp -a /etc/scylla/scylla.yaml /etc/scylla/scylla.yaml.backup-src
+   sudo cp -a /etc/scylla/scylla.yaml /etc/scylla/scylla.yaml.backup
+   sudo cp /etc/yum.repos.d/scylla.repo ~/scylla.repo-backup
 
 Stop ScyllaDB
 ---------------
@@ -122,29 +127,33 @@ Rollback Steps
 ==============
 Gracefully shutdown ScyllaDB
 -----------------------------
+
 .. code:: sh
 
    nodetool drain
- .. include:: /rst_include/scylla-commands-stop-index.rst
+   nodetool snapshot
+   sudo service scylla-server stop
 
-Download and install the old release
+Restore and install the old release
 ------------------------------------
-#. Remove the old repo file.
+#. Restore the |SRC_VERSION| packages backed up during the upgrade.
 
     .. code:: sh
 
-       sudo rm -rf /etc/yum.repos.d/scylla.repo
+       sudo cp ~/scylla.repo-backup /etc/yum.repos.d/scylla.repo
+       sudo chown root.root /etc/yum.repos.d/scylla.repo
+       sudo chmod 644 /etc/yum.repos.d/scylla.repo
 
-#. Update the |SCYLLA_REPO|_  to |SRC_VERSION|.
 #. Install:
 
     .. code:: console
 
        sudo yum clean all
        sudo rm -rf /var/cache/yum
-       sudo yum remove scylla\\*tools-core
-       sudo yum downgrade scylla\\* -y
-       sudo yum install scylla
+       sudo yum downgrade scylla-\*cqlsh -y
+       sudo yum remove scylla-\*cqlsh -y
+       sudo yum downgrade scylla\* -y
+       sudo yum install scylla -y
      
 
 Restore the configuration file
@@ -153,18 +162,7 @@ Restore the configuration file
 .. code:: sh
 
    sudo rm -rf /etc/scylla/scylla.yaml
-   sudo cp -a /etc/scylla/scylla.yaml.backup-src | /etc/scylla/scylla.yaml
-
-Restore system tables
----------------------
-
-Restore all tables of **system** and **system_schema** from previous snapshot because |NEW_VERSION| uses a different set of system tables. See :doc:`Restore from a Backup and Incremental Backup </operating-scylla/procedures/backup-restore/restore/>` for details.
-
-.. code:: sh
-
-    cd /var/lib/scylla/data/keyspace_name/table_name-UUID/snapshots/<snapshot_name>/
-    sudo cp -r * /var/lib/scylla/data/keyspace_name/table_name-UUID/
-    sudo chown -R scylla:scylla /var/lib/scylla/data/keyspace_name/table_name-UUID/
+   sudo cp /etc/scylla/scylla.yaml-backup /etc/scylla/scylla.yaml
 
 Reload systemd configuration
 ---------------------------------

docs/upgrade/_common/upgrade-guide-v5-ubuntu-and-debian-p1.rst

@@ -60,9 +60,13 @@ When the upgrade is completed on all nodes, remove the snapshot with the ``nodet
 Backup the configuration file
 ------------------------------
 
+Back up the ``scylla.yaml`` configuration file and the ScyllaDB packages
+in case you need to rollback the upgrade.
+
 .. code:: sh
 
-   sudo cp -a /etc/scylla/scylla.yaml /etc/scylla/scylla.yaml.backup-src
+   sudo cp -a /etc/scylla/scylla.yaml /etc/scylla/scylla.yaml.backup
+   sudo cp /etc/apt/sources.list.d/scylla.list ~/scylla.list-backup
 
 Gracefully stop the node
 ------------------------

docs/upgrade/_common/upgrade-guide-v5-ubuntu-and-debian-p2.rst

@@ -44,7 +44,6 @@ For each of the nodes you rollback to |SRC_VERSION|, you will:
 * Drain the node and stop Scylla
 * Retrieve the old ScyllaDB packages
 * Restore the configuration file
-* Restore system tables
 * Reload systemd configuration
 * Restart ScyllaDB
 * Validate the rollback success
@@ -59,17 +58,19 @@ Gracefully shutdown ScyllaDB
 .. code:: sh
 
    nodetool drain
+   nodetool snapshot
    sudo service scylla-server stop
 
-Download and install the old release
+Restore and install the old release
 ------------------------------------
-#. Remove the old repo file.
+#. Restore the |SRC_VERSION| packages backed up during the upgrade.
 
     .. code:: sh
 
-       sudo rm -rf /etc/apt/sources.list.d/scylla.list
+       sudo cp ~/scylla.list-backup /etc/apt/sources.list.d/scylla.list
+       sudo chown root.root /etc/apt/sources.list.d/scylla.list
+       sudo chmod 644 /etc/apt/sources.list.d/scylla.list
 
-#. Update the |SCYLLA_REPO|_ to |SRC_VERSION|.
 #. Install:
 
     .. code-block::
@@ -85,18 +86,7 @@ Restore the configuration file
 .. code:: sh
 
    sudo rm -rf /etc/scylla/scylla.yaml
-   sudo cp -a /etc/scylla/scylla.yaml.backup-src | /etc/scylla/scylla.yaml
-
-Restore system tables
----------------------
-
-Restore all tables of **system** and **system_schema** from the previous snapshot because |NEW_VERSION| uses a different set of system tables. See :doc:`Restore from a Backup and Incremental Backup </operating-scylla/procedures/backup-restore/restore/>` for reference.
-
-.. code:: sh
-
-    cd /var/lib/scylla/data/keyspace_name/table_name-UUID/snapshots/<snapshot_name>/
-    sudo cp -r * /var/lib/scylla/data/keyspace_name/table_name-UUID/
-    sudo chown -R scylla:scylla /var/lib/scylla/data/keyspace_name/table_name-UUID/
+   sudo cp /etc/scylla/scylla.yaml-backup /etc/scylla/scylla.yaml
 
 Reload systemd configuration
 ----------------------------