fix(tablets): remove tablets from experimental features

[yarongilor]

fix(tablets): remove tablets and consistent-topology-changes from experimental features

        tablets feature is not experimental anymore and is default
        to be enabled. tablets is dependent on consistent-topology-changes.
        refs: https://github.com/scylladb/scylladb/pull/18898

refs: scylladb/scylladb#18898

i'm not sure this PR is needed and about its dependencies or anything else..
The PR also assumes there's no need of updating scylla yaml with: "enable_tablets": "false"

Testing

• [ ]

PR pre-checks (self review)

• I added the relevant backport labels
• I didn't leave commented-out/debugging code

Reminders

• Add New configuration option and document them (in sdcm/sct_config.py)
• Add unit tests to cover my changes (under unit-test/ folder)
• Update the Readme/doc folder relevant to this change (if needed)

[bhalevy]

Is this still true? Do we disable raft by default?

[yarongilor]

IIUC this flag is not relevant anymore, unless still relevant to only 1 out of 2 raft features. @aleksbykov , @roydahan , can you please confirm?

[roydahan]

Probably not.
@aleksbykov / @temichus ?

[aleksbykov]

This flag is only was used for rolling upgrade tests. Job with disabled raft uses additional yaml with relevant

[bhalevy]

Should we instead edit scylla.yaml to remove the newly introduced enable_tablets config option?
(See scylladb/scylladb#18898)

[roydahan]

@yarongilor your PR shouldn't touch raft experimntal - @aleksbykov / @temichus please organise it so whatever should be tested with "raft disabled" (consistent-topology) is correctly configured and remove all the unnecessary flags / configurations.

@yarongilor your PR should flip the flag, now to support "disabling" tablets and have the duplicated jobs that are testing tablets with "disabled raft" - @aleksbykov & @temichus should be synced because some of these should be for 6.0 (so maybe they already working on it).

[yarongilor]

@yarongilor your PR shouldn't touch raft experimntal - @aleksbykov / @temichus please organise it so whatever should be tested with "raft disabled" (consistent-topology) is correctly configured and remove all the unnecessary flags / configurations.

@yarongilor your PR should flip the flag, now to support "disabling" tablets and have the duplicated jobs that are testing tablets with "disabled raft" - @aleksbykov & @temichus should be synced because some of these should be for 6.0 (so maybe they already working on it).

Conclusions:
This PR will only change tablets flag and will modify a directory to have tablets disabled.
The upgrade will also be adjusted to add the tablets flag.

@roydahan , @ShlomiBalalis , please advise - one thing we have to confirm is the tablets supported nemeses.
Currently, when tablets are enabled by default, the file of "configurations/tablets_supported_nemeses.yaml" is meaningless. All nemeses are now used with tablets in all jobs.
So if it is confirmed, the above file could be removed.
The last configuration is 37 out of 91 nemeses are not supported -

$ grep "\- disrupt_" nemesis.yml -c
91
$ grep "tablets_phase_1_supported = False" nemesis.yml -c
37

cc: @bhalevy

[yarongilor]

Addressed in #7295 and #7655