REGTESTS: Do not use REQUIRE_VERSION for HAProxy 2.5+

Introduced in:

0657b9338 MINOR: stream: add "last_rule_file" and "last_rule_line" samples
diff --git a/reg-tests/log/last_rule.vtc b/reg-tests/log/last_rule.vtc
index b572519..e695166 100644
--- a/reg-tests/log/last_rule.vtc
+++ b/reg-tests/log/last_rule.vtc
@@ -1,7 +1,7 @@
 varnishtest "Verify logging of last final rule"
-feature ignore_unknown_macro
 
-#REQUIRE_VERSION=2.6
+feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.6-dev0)'"
+feature ignore_unknown_macro
 
 server s1 {
     rxreq