Cherry-pick: Fix: system.databases always shows data lake catalog databases

[zvonand]

Cherry-picked from ClickHouse#103444.

Fix: system.databases always shows data lake catalog databases

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system.databases now lists data lake catalog databases regardless of the show_data_lake_catalogs_in_system_tables setting.

The setting exists to prevent accidental expensive calls to remote catalog services (e.g. listing tables or columns). Knowing that a catalog database exists, however, requires no remote call — the DatabaseCatalog already keeps it in local memory. Hiding the database in system.databases based on that setting was inconsistent with SHOW DATABASES (which always showed catalogs since ClickHouse#89914) and confusing for users.

Changes:

• StorageSystemDatabases::fillData now passes with_datalake_catalogs = true unconditionally.
• InterpreterShowTablesQuery::execute no longer needs to force the setting for SHOW DATABASES (the rewrite to system.databases already returns the right result). The HACK is retained only for SHOW TABLES FROM <datalake_catalog> which still needs it.
• Updated test_database_glue integration test to assert that system.databases shows the catalog even with the setting off.

Followup to: ClickHouse#89914

Changelog category (leave one):

• Improvement

Changelog entry

SELECT * FROM system.databases now always lists data lake catalog databases regardless of the show_data_lake_catalogs_in_system_tables setting. Previously they were hidden by default, which was inconsistent with SHOW DATABASES that always showed them.

[github-actions]

Workflow [PR], commit [8a342fd]