Replace the deprecated rsyslog config style

The old style has been deprecated for time:
http://www.rsyslog.com/doc/v8-stable/compatibility/v7compatibility.html#omruleset-and-discard-action-are-deprecated
TrivialFix

Change-Id: I70fa065f5fbd686ddb8f4134bb93c08c7af00365

ansible/roles/common/templates/rsyslog.conf.j2

@@ -140,5 +140,7 @@ $template MagnumConductorFile,"/var/log/magnum/magnum-conductor.log"
 :syslogtag,contains,"magnum-conductor" ?MagnumConductorFile
 
 $template DynFile,"/var/log/syslog.log"
-*.* ?DynFile
-& ~
+*.* {
+  ?DynFile
+  stop
+}