kvserver: make all cluster settings system only

[kvoli]

98347 covers updating distribution cluster settings in the kvserver pkg to be SystemOnly. This issue tracks changing any other cluster settings in the kvserver pkg to be SystemOnly.

The remaining cluster settings are depended on by tests using a non-system tenant to modify the setting. Updating these settings from TenantWritable or TenantReadOnly, to SystemOnly will require updating fixing tests.

Complete list

``` kv.rangefeed.enabled kv.closed_timestamp.target_duration kv.closed_timestamp.side_transport_interval kv.raft.command.max_size kv.protectedts.reconciliation.interval kv.protectedts.poll_interval kv.protectedts.max_bytes kv.gc_ttl.strict_enforcement.enabled server.time_until_store_dead ```

The most depended (of tests using a non-system tenant) are kv.rangefeed.enabled or kv.closed_timestamp.target_duration.

Jira issue: CRDB-25464

[andrewbaptist]

Just as a reminder - we should update server.time_until_store_dead to not be tenant writable.