mon: s/assert/ceph_assert/g'

mon: s/assert/ceph_assert/g'

Now that we fallback to RelDebWithInfo [1], C asserts are not compiled
in.
Replace some of the existing asserts with ceph_assserts instead.

[1] #61637

Fixes: https://tracker.ceph.com/issues/71360
Signed-off-by: Matan Breizman <mbreizma@redhat.com>