fix: replace 'e.message' with str(e) and add @with_object_filters to ServerNode.list

Two pre-existing master bugs surfaced by the data-isolation regression
tests:

1. 'e.message' on caught exceptions (13 sites). Exception.message was
   removed in Python 3 (it lived on BaseException in Py2). When the
   except handler runs, accessing e.message raises AttributeError,
   masking the original exception. Werkzeug HTTPException doesn't
   expose .message either - it uses .description / .__str__.

   Replace 'e.message' with str(e) across:
   - browser/server_groups/__init__.py (delete/update/create handlers)
   - browser/server_groups/servers/__init__.py (5 handlers)
   - browser/server_groups/servers/databases/__init__.py
   - misc/cloud/__init__.py
   - tools/debugger/__init__.py
   - tools/grant_wizard/__init__.py (2 sites)

   Sites guarded by hasattr(e, 'message') first (psycopg3 driver) are
   left as-is; module.messages dict access (utils/__init__) is also
   unrelated.

2. ServerNode.list() missing @with_object_filters decorator. PR #8917
   (99b822e47) added object_filters as a required positional arg to
   list() but only added the @with_object_filters decorator to
   get_nodes(), leaving list() with a signature the Flask routing
   couldn't satisfy. Surfaced by SharedServersGetTestCase 'Get a all
   shared server' test, which calls the list endpoint directly.