[OVN] Ensure socket files are absent in init_ovn

Just like we remove db files let's also remove
socket files when initializing ovn. Those will
reappear once service fully restarts along with
db files. Without it we see random issue as
described in the below bug.

Closes-Bug: #2002629
Change-Id: I726a9cac9c805d017273aa79e844724f0d00cdf0
(cherry picked from commit 7fecba2f13)

lib/neutron_plugins/ovn_agent

@@ -577,6 +577,7 @@ function init_ovn {
     rm -f $OVS_DATADIR/.*.db.~lock~
     sudo rm -f $OVN_DATADIR/*.db
     sudo rm -f $OVN_DATADIR/.*.db.~lock~
+    sudo rm -f $OVN_RUNDIR/*.sock
 }
 
 function _start_ovs {