ceph_key: restore file mode after a key is fetched

ceph_key: restore file mode after a key is fetched

when `import_key` is enabled, if the key already exists, it will only be
fetched using ceph cli, if the mode specified in the `ceph_key` task is
different from what is applied by the ceph cli, the mode isn't restored because
we don't call `module.set_fs_attributes_if_different()` before
`module.exit_json(**result)`

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1734513
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit b717b5f736448903c69882392e0691fba60893aa)