REGTEST: lua/b00003: Specify the HAProxy pid when the command ss is executed

This avoids confusions with any other haproxy process.
diff --git a/reg-tests/lua/b00003.vtc b/reg-tests/lua/b00003.vtc
index f58229b..3fd70eb 100644
--- a/reg-tests/lua/b00003.vtc
+++ b/reg-tests/lua/b00003.vtc
@@ -48,6 +48,6 @@
 syslog Slog -wait
 
 shell {
-    ss -pt | grep CLOSE-WAIT.*haproxy
+    ss -pt | grep CLOSE-WAIT.*haproxy.*pid=${h1_pid}
     exit $((!$?))
 }