Add CI job to test buildbox-run-bubblewrap and buildbox-fuse

This adds a CI job to test buildbox-run with buildbox-run-bubblewrap and buildbox-fuse. It is based on top of !1738 (merged) and depends on buildstream-docker-images!150 (merged).

This also drops the previous buildbox sandboxing backend as that's now fully replaced by the new buildbox-run sandboxing backend.

Fixes: #1226 (closed)