fix(setup): split membership fields migration (#9230)

# Which Problems Are Solved

The membership fields migration timed out in certain cases. It also
tried to migrate instances which were already removed.

# How the Problems Are Solved

Revert the previous fix that combined the repeatable step for multiple
fill triggers. The membeship migration is now single-run as it might
take a lot of time. It is not worth making it repeatable. Instance IDs
of removed instances are skipped.

# Additional Changes

None

# Additional Context

Introduced in https://github.com/zitadel/zitadel/pull/9199

cmd/setup/46/06-permitted_orgs_function.sql

@@ -44,7 +44,7 @@ BEGIN
 		WHERE om.role = ANY(matched_roles)
 		AND om.instance_id = instanceID
 		AND om.user_id = userId
-	) AS orgs;
+	);
     RETURN;
 END;
 $$;