Before this commit, when the underlying materialized view was created,
it didn't have the property `tombstone_gc` set to any value. We fix the
bug in this PR.
Implementation strategy:
1. Move code responsible for producing the schema
of a secondary index to the file that handles
`CREATE INDEX`.
2. Set the property when creating the view.
3. Add reproducer tests.
Fixesscylladb/scylladb#26542
Backport: we can discuss it.
Closesscylladb/scylladb#26543
* github.com:scylladb/scylladb:
index: Set tombstone_gc when creating secondary index
index: Make `create_view_for_index` method of `create_index_statement`
index: Move code for creating MV of secondary index to cql3
db, cql3: Move creation of underlying MV for index
f3cec5f11a