Add ceph_nfs_adopt tag to the cephadm-adopt playbook

Add ceph_nfs_adopt tag to the cephadm-adopt playbook

There are existing OpenStack scenarios where nfs is still not managed
by cephadm. For this reason sometimes is useful skip the nfs part of
the adoption playbook and leave this daemon unmanaged.
The purpose of this patch is providing a tag to enable the OpenStack
operators to skip this playbook section.

Closes: https://bugzilla.redhat.com/2009212
Signed-off-by: Francesco Pantano <fpantano@redhat.com>
(cherry picked from commit b7299f258b607dc57e4c9c0ce693261a736d1777)