dmeventd: reintroduce fix mirror DSO to work with lvmetad

Commit 07ded8059c assumed that the mirror is blocked which is not the case.

It is accessible, degraded and in need of repair because some of its legs
(partially) failed.  Any auto-repair via dmeventd fails though because
of lvmetad not providing proper data about the failed PV(s).  That's why
this workaround got introduced in commit 76f6951c3e until we get to
the lvmetad interaction core issue.

Mind any mirror auto-repair failure is caused by such lvmetad interaction
problems not yet solved so disabling lvmetad works as a resort as elaborated
on in the related bz.

Reintroducing the interim solution.

Resolves: rhbz1380521

daemons/dmeventd/plugins/mirror/dmeventd_mirror.c

@@ -188,7 +188,7 @@ int register_device(const char *device,
 
         /* CANNOT use --config as this disables cached content */
 	if (!dmeventd_lvm2_command(state->mem, state->cmd_lvconvert, sizeof(state->cmd_lvconvert),
-				   "lvconvert --repair --use-policies", device))
+				   "lvconvert --config global{use_lvmetad = 0}' --repair --use-policies", device))
 		goto_bad;
 
 	*user = state;