debian: set rest-bench-dbg ceph-test-dbg dependencies

debian: set rest-bench-dbg ceph-test-dbg dependencies

Debian's debug packages ought to depend on their respective binary
packages. This was the case for many of our ceph packages, but it was
not the case for ceph-test-dbg or rest-bench-dbg.

Add the dependencies on the relevant binary packages, pinned to
"= ${binary:Version}" per convention.

http://tracker.ceph.com/issues/11673 Fixes: #11673

Signed-off-by: Ken Dreyer <kdreyer@redhat.com>