This fixes an issue where materialized view tablets are not split
because they are not registered as split candidates by the storage
service.
The code in storage_service::replicate_to_all_cores was changed in
4bfa3060d0 to handle normal tables and view tables separately, but with
that change register_tablet_split_candidate is applied only to normal
tables and not every table like before. We fix it by registering view
tables as well.
We add a test to verify that split of MV tables works.
Closesscylladb/scylladb#23335
49b8cf2d1d