Submitted by: @mrotteveel

A user executing ALTER ROLE without ALTER ANY ROLE privilege is shown the wrong error message.

Current behaviour:

```
alter role rdb$admin set auto admin mapping;
Statement failed, SQLSTATE = 28000
unsuccessful metadata update
-CREATE OR ALTER MAPPING AutoAdminImplementationMapping failed
-Unable to perform operation
-System privilege CHANGE_MAPPING_RULES is missing
```

The error indicates that executing ALTER ROLE was allowed, but only the attempt to then create a mapping fails.

As error message I would expect:

"""
Statement failed, SQLSTATE = 28000
unsuccessful metadata update
-ALTER ROLE RDB$ADMIN failed
-no permission for ALTER access to ROLE RDB$ADMIN
-Effective user is TESTUSER
"""