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
We add a reproducing test for issue #8138, were if we write to an
TWCS table, scanning it would yield no rows - and worse - crash the
debug build.
This test requires "nodetool flush" to force the read to happen from
sstables, hence the nodetool feature was implemented in the previous
patch (on Scylla, it uses the REST API - not actually running nodetool
or requiring JMX).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
