chore: remove redundant grants

Author: soedirgo

migrations/db/migrations/20240319072844_lock_down_postgres_access_to_auth_migrations.sql

@@ -1,6 +1,4 @@
 -- migrate:up
 revoke supabase_auth_admin from postgres;
-revoke all on table auth.schema_migrations from postgres;
-grant select on table auth.schema_migrations to postgres;
 
 -- migrate:down

migrations/tests/database/privs.sql

@@ -29,6 +29,5 @@ SELECT schema_privs_are('extensions', 'anon', array['USAGE']);
 SELECT schema_privs_are('extensions', 'authenticated', array['USAGE']);
 SELECT schema_privs_are('extensions', 'service_role', array['USAGE']);
 
--- Verify auth schema privileges
-SELECT schema_privs_are('auth', 'postgres', array['CREATE', 'USAGE']);
-SELECT table_privs_are('auth', 'schema_migrations', 'postgres', array['SELECT']);
+-- Role memberships
+SELECT isnt_member_of('supabase_auth_admin', 'postgres');