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
Closesscylladb/scylladb#16155