If the user wants to change the default initial tablets value, it uses ALTER KEYSPACE statement. However, specifying `WITH tablets = { initial: $value }` will take no effect, because statement analyzer only applies `tablets` parameters together with the `replication` ones, so the working statement should be `WITH replication = $old_parameters AND tablets = ...` which is not very convenient.
This PR changes the analyzer so that altering `tablets` happens independently from `replication`. Test included.
fixes: #18801Closesscylladb/scylladb#18899
* github.com:scylladb/scylladb:
cql-pytest: Add validation of ALTER KEYSPACE WITH TABLETS
cql3: Fix parsing of ALTER KEYSPACE's tablets parameters
cql3: Remove unused ks_prop_defs/prepare_options() argument