debian/rules: strip ceph-osd-classic and ceph-osd-crimson
override_dh_strip enumerates each binary package explicitly. It was not
updated when ceph-osd was split into the ceph-osd-classic and
ceph-osd-crimson implementation packages, so the OSD binaries in those
two packages are shipped unstripped (ceph-osd-crimson installs at ~4.6
GiB) and their -dbg packages are left empty.
Add the missing dh_strip invocations so the OSD binaries are stripped
and their debug symbols land in the corresponding -dbg packages, as is
already done for every other binary package.