OSDs are not migrated from filestore to bluestore

Issue

• We followed the documentation to migrate OSDs from filestore to bluestore
• However even after the openstack overcloud external-upgrade run ... command completed without error, ods are still using filestore

[stack@undercloud-0 ~]$ openstack overcloud external-upgrade run --tags ceph_fstobs -e ceph_ansible_limit=ceph-0| tee oc-fstobs.log
...
Success

[root@controller-0 ~]# podman exec -it ceph-mon-controller-0 sh -c "ceph -f json osd metadata" | jq -c '.[] | select(.hostname == "ceph-0") | ["host", .hostname, "osd_id", .id, "objectstore", .osd_objectstore]'
["host","ceph-0","osd_id",0,"objectstore","filestore"]
["host","ceph-0","osd_id",1,"objectstore","filestore"]
...