Pending minor changes for 6.0

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This issue is for tracking minor changes blocking on an upstream EF Core change.

Pending

• After Fix some test determinism issue dotnet/efcore#25572, remove overrides for Where_collection_navigation_ToList_Contains, Where_collection_navigation_ToArray_Contains, Where_collection_navigation_AsEnumerable_Contains, SelectMany_with_client_eval_with_constructor (see 4a3c035)
• After Relational: IS (NOT) NULL requires parenthesis when not in left side of an equality dotnet/efcore#23990 is done, remove our own bracket logic for IS NULL.
• Unskip NorthwindSelectQueryNpgsqlTest.Project_to_object_array after we figure out what to do with Convert-to-object nodes not bubbling up type mappings (conversation with @smitpatel).

Done

• After SharedTypeQueryRelationalTestBase does not delimit identifiers in raw SQL dotnet/efcore#25661, unskip Can_use_shared_type_entity_type_in_query_filter_with_from_sql
• Reenable UdfDbFunctionNpgsqlTests once the built-in/schema stuff is sorted out (Allow schema-less UDFs to not be built-in dotnet/efcore#23829)