This series adds notification before dropping views and indices so that the
tablet_allocator can generate mutations to respectively drop all tablets associated with them from system.tablets.
Additional unit tests were added for these cases.
Note that one case is not yet tested: where a table is allowed to be dropped while having views that depend on it, when it is dropped from the alternator path.
This is tested indirectly by testing dropping a table with live secondary index as it follows the same notification path as views in this series.
Fixes#17627Closesscylladb/scylladb#17773
* github.com:scylladb/scylladb:
migration_manager: notify before_drop_column_family when dropping indices
schema_tables: make_update_indices_mutations: use find_schema to lookup the view of dropped indices
migration_manager: notify before_drop_column_family before dropping views
cql-pytest: test_tablets: add test_tablets_are_dropped_when_dropping_table
tablet_allocator: on_before_drop_column_family: remove unused result variable
8c5d088928