Update visibility for serverless

[tvernum]

This commit reconciles the spec against the server implementation.

The specification's '@available serverless' annotations now match the @ServerlessScope annotations in the Elasticsearch Java code.

[JoshMock]

Not sure how we missed this. LGTM.

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
cat.health	🟢	5/5	5/5
cat.recovery	🟢	6/6	6/6
cat.repositories	🟢	6/6	6/6
cluster.get_settings	🟢	7/7	7/7
cluster.pending_tasks	🟢	3/3	3/3
cluster.put_settings	🟢	27/27	26/26
cluster.stats	🟢	8/8	8/8
delete_by_query_rethrottle	🟢	1/1	1/1
eql.delete	🟢	3/3	3/3
eql.get_status	🟢	3/3	3/3
eql.get	🟢	2/2	2/2
eql.search	🟢	24/24	24/24
explain	🟢	14/14	14/14
features.reset_features	⚪	Missing test	Missing test
health_report	⚪	Missing test	Missing test
indices.add_block	🟢	2/2	2/2
indices.clear_cache	🟢	4/4	4/4
indices.delete_template	🟢	9/9	9/9
indices.disk_usage	🟢	1/1	1/1
indices.exists_template	🟢	15/15	15/15
indices.field_usage_stats	🟢	5/5	5/5
indices.flush	🟢	9/9	9/9
indices.forcemerge	🔴	4/4	3/4
indices.get_template	🟢	30/30	30/30
indices.refresh	🟢	202/202	202/202
indices.segments	🔴	6/6	5/6
license.get	🟢	6/6	6/6
nodes.clear_repositories_metering_archive	⚪	Missing test	Missing test
nodes.get_repositories_metering_info	⚪	Missing test	Missing test
reindex_rethrottle	🟢	2/2	2/2
reindex	🟢	15/15	14/14
security.clear_api_key_cache	🟢	9/9	9/9
security.has_privileges	🟢	9/9	9/9
slm.delete_lifecycle	🟢	4/4	4/4
slm.execute_lifecycle	🟢	4/4	4/4
slm.execute_retention	🟢	4/4	4/4
slm.get_lifecycle	🟢	16/16	16/16
slm.get_stats	🟢	4/4	4/4
slm.get_status	🟢	4/4	4/4
slm.put_lifecycle	🟢	4/4	4/4
slm.start	⚪	Missing test	Missing test
slm.stop	🟢	4/4	4/4
snapshot.cleanup_repository	🟢	3/3	3/3
snapshot.clone	🟢	5/5	5/5
snapshot.create_repository	🟢	26/26	26/26
snapshot.create	🟢	25/25	25/25
snapshot.delete_repository	🟢	10/10	10/10
snapshot.delete	🟢	19/19	19/19
snapshot.get_repository	🟢	19/19	19/19
snapshot.get	🟢	12/12	12/12
snapshot.restore	🟢	5/5	5/5
snapshot.status	🟢	2/2	2/2
snapshot.verify_repository	🟢	2/2	2/2
sql.clear_cursor	🟢	1/1	1/1
sql.delete_async	⚪	Missing test	Missing test
sql.get_async_status	⚪	Missing test	Missing test
sql.get_async	⚪	Missing test	Missing test
sql.query	🟢	5/5	5/5
sql.translate	🟢	1/1	1/1
tasks.cancel	🟢	2/2	2/2
tasks.get	🟢	10/10	10/10
tasks.list	🟢	8/8	8/8
update_by_query_rethrottle	🟢	1/1	1/1
xpack.usage	🔴	19/19	0/15

You can validate these APIs yourself by using the make validate target.