tests: update default value for CEPH_STABLE_RELEASE

tests: update default value for CEPH_STABLE_RELEASE

- update value for `CEPH_STABLE_RELEASE`: next release will ship with
`nautilus`. This variable is used for stable branch only, this way, it
will be ready when next stable version will be released.

- test upgrade from mimic to ceph@master: don't run dev_setup.yml on update
scenario, and run it in [update] section so we update from mimic to
ceph@master.

- run lvm_setup.yml for all scenarios except `lvm_batch`

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>