Add sharding key `group_id` to agent_user_access_group_authorizations

This table has been identified as a cell local table.

All cell local tables require a sharding key.

A sharding key has been automatically selected for this table. group_id was chosen because it is a NOT NULL column referencing either projects or namespaces.

Please confirm that this table should indeed be cell local, and that group_id is an appropriate sharding key.

When updating the gitlab_schema we have also added allow_cross_joins, allow_cross_transactions and allow_cross_foreign_keys. You can read about this in https://docs.gitlab.com/ee/development/database/multiple_databases.html but basically for now we want to ignore any of these violations and just classify the tables that belong to gitlab_main_cell. In future we'll remove these allow_... statements so that we can fix these violations.

If you have any questions or concerns, reach out to @tigerwnz or @DylanGriffith.

This merge request was created using the gitlab-housekeeper gem.