scripts/build_utils: remove Debug build from Crimson
See: https://github.com/ceph/ceph-build/pull/2167/files
Builds should be set to Debug only when ending in "-debug".
https://github.com/ceph/ceph-build/pull/1805 set Crimson to always use Debug.
That made sense in earlier development phases.
However, today we should align with Classical builds and use Debug only when needed.