Added fault tolerance force kill for salt-minion upon stop/start
to avoid rare issue when multiply salt-minion instances launched

Prod related: (PROD:26113)

Change-Id: Ifdf1b41a5abb430bb88017112fe89ffec799eacf
diff --git a/salt/files/systemd/salt-minion.service_50-restarts b/salt/files/systemd/salt-minion.service_50-restarts
index 5dee5d7..d37f6a7 100644
--- a/salt/files/systemd/salt-minion.service_50-restarts
+++ b/salt/files/systemd/salt-minion.service_50-restarts
@@ -1,3 +1,5 @@
 [Service]
 Restart=always
-RestartSec=3
+RestartSec=15
+ExecStartPre=-/usr/bin/pkill --ns 1 -x -9 salt-minion
+ExecStopPost=-/usr/bin/pkill --ns 1 -x -9 salt-minion