mgr/dashboard: fix bucket rate limit API on owner change

mgr/dashboard: fix bucket rate limit API on owner change

Fixes: https://tracker.ceph.com/issues/70874
PR covers & fixes below scenarios:
Whenever we change the owner of bucket from non-tenanted to tenanted and
vice-versa with the rate-limit changes, there was issue in sending bucket name
Scenario 1: Changing the bucket owner from tenanted to non-tenanted
Scenario 2: Changing the bucket owner from non-tenanted to tenanted
Scenario 3: Keeping the owner(tenanted) same and changing only rate limit

Signed-off-by: Naman Munet <naman.munet@ibm.com>