REGTESTS: webstats: remove unused stats socket in /tmp

Remove a useless stats socket which was configured outside the reg-tests
directories.
diff --git a/reg-tests/webstats/webstats-scope-and-post-change.vtc b/reg-tests/webstats/webstats-scope-and-post-change.vtc
index b88287a..e896c05 100644
--- a/reg-tests/webstats/webstats-scope-and-post-change.vtc
+++ b/reg-tests/webstats/webstats-scope-and-post-change.vtc
@@ -12,8 +12,6 @@
     # under us.
     tune.idle-pool.shared off
 
-    stats socket /tmp/haproxy.socket level admin
-
   defaults
     mode http