REGTEST: Add option to use HTX prefixed by the macro 'no-htx'

So some tests have been removed.
diff --git a/reg-tests/http-cookies/h00000.vtc b/reg-tests/http-cookies/h00000.vtc
index 3ea16ac..f599a0f 100644
--- a/reg-tests/http-cookies/h00000.vtc
+++ b/reg-tests/http-cookies/h00000.vtc
@@ -31,6 +31,7 @@
 
     defaults
         mode http
+        ${no-htx} option http-use-htx
 		option httplog
         timeout client 1s
         timeout server 1s