mgr/dashboard: Fix pool renaming functionality

mgr/dashboard: Fix pool renaming functionality

The problem was that, if a pool was renamed the routine to update tried
to work on the old pool name and didn't used the info that the pool got
renamed, therefore an error occurred in the UI saying that the pool
could not be found.

Fixes: https://tracker.ceph.com/issues/42776
Signed-off-by: Stephan Müller <smueller@suse.com>
(cherry picked from commit de933cd3c82b6a7d5c4ddfa77804509c9fcaa3db)

Conflicts:
      qa/tasks/mgr/dashboard/test_pool.py:
      - Ignore incoming quota test