ceph.spec.in: Include Crimson by default in RPM builds

ceph.spec.in: Include Crimson by default in RPM builds

With #65782 merged, Crimson could be now built as part of the default RPM build flavor.
The binaries ceph-osd-crimson and ceph-osd-classic are managed via `update-alternatives`
and selected based on priority:

- ceph-osd-classic keeps the **highest** priority (100) and remains the default.
- Switching to crimson is possible via:
  update-alternatives --set ceph-osd /usr/bin/ceph-osd-crimson

Existing classic behavior remains unchanged unless the above command is explicitly executed.

Signed-off-by: Matan Breizman <mbreizma@redhat.com>