Current upgrade dtest rely on a ccm node function to
get_highest_supported_sstable_version() that looks for
r'Feature (.*)_SSTABLE_FORMAT is enabled' in the log files.
Starting from scylla-6.0 ME_SSTABLE_FORMAT is enabled by default
and there is no cluster feature for it. Thus get_highest_supported_sstable_version()
returns an empty list resulting in the upgrade tests failures.
This change introduces a seperate API path that returns the highest
supported sstable format (one of la, mc, md, me) by a scylla node.
Fixesscylladb/scylladb#19772
Backports to 6.0 and 6.1 required. The current upgrade test in dtest
checks scylla upgrades up to version 5.4 only. This patch is a
prerequisite to backport the upgrade tests fix in dtest.
Closesscylladb/scylladb#19787
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
