mds: use bash for executing liveness probe script

This script includes bash features and will fail if sh is not a symlink to bash.

Signed-off-by: José Martínez <xose@google.com>
(cherry picked from commit e421623fd0)

pkg/operator/ceph/file/mds/livenessprobe.go

@@ -74,7 +74,7 @@ func generateMDSLivenessProbeExecDaemon(daemonID, filesystemName, keyring string
 		ProbeHandler: v1.ProbeHandler{
 			Exec: &v1.ExecAction{
 				Command: []string{
-					"sh",
+					"bash",
 					"-c",
 					mdsLivenessProbeCmd,
 				},