mds: dump_values no more needed

mds: dump_values no more needed

Previouly, two individual scrubs were initiated to scrub ~mdsdir
at root where the ~mdsdir scrub wasn't provided any tag thus, it
was necessary to not dump it's values for output of 'scrub start'.
Now since mdsdir and root scrub run under single header, there is
no need for this anymore, thus removing this redundant code.

Fixes: https://tracker.ceph.com/issues/59350
Signed-off-by: Dhairya Parmar <dparmar@redhat.com>