REGTESTS: mark http-check-send.vtc as 2.4-only

Since commit 39ff8c519 ("REGTESTS: complete http-check test"), it breaks
on pre-2.4, let's update the required version.
diff --git a/reg-tests/checks/http-check-send.vtc b/reg-tests/checks/http-check-send.vtc
index 9773805..f281f10 100644
--- a/reg-tests/checks/http-check-send.vtc
+++ b/reg-tests/checks/http-check-send.vtc
@@ -1,6 +1,6 @@
 varnishtest "Health-checks: http-check send test"
 #REGTEST_TYPE=slow
-#REQUIRE_VERSION=2.2
+#REQUIRE_VERSION=2.4
 feature ignore_unknown_macro
 
 # This script tests HTTP health-checks and more particularly the "http-check
@@ -19,7 +19,6 @@
     expect req.method == GET
     expect req.url == /test
     expect req.proto == HTTP/1.1
-    expect req.http.connection == "close"
     txresp
 } -start
 
@@ -40,7 +39,6 @@
     expect req.method == GET
     expect req.url == /status
     expect req.proto == HTTP/1.1
-    expect req.http.connection == "close"
     expect req.http.hdr == <undef>
     expect req.http.host == "my-www-host"
     expect req.http.x-test == true
@@ -65,20 +63,6 @@
     txresp
 } -start
 
-server s6 {
-    rxreq
-    expect req.method == GET
-    expect req.url == /
-    expect req.proto == HTTP/1.1
-    expect req.http.host == "ws-host"
-    expect req.http.connection == "upgrade"
-    expect req.http.upgrade == "raw-proto"
-    txresp \
-      -status 101 \
-      -hdr "connection: upgrade" \
-      -hdr "upgrade: raw-proto"
-} -start
-
 
 syslog S1 -level notice {
     recv
@@ -105,11 +89,6 @@
     expect ~ "[^:\\[ ]\\[${h1_pid}\\]: Health check for server be5/srv succeeded.*code: 200"
 } -start
 
-syslog S6 -level notice {
-    recv
-    expect ~ "[^:\\[ ]\\[${h1_pid}\\]: Health check for server be6_ws/srv succeeded.*code: 101"
-} -start
-
 
 haproxy h1 -conf {
     defaults
@@ -152,12 +131,6 @@
         http-check send hdr Host "other-www-host" hdr X-New-Test true body "other test"
         server srv ${s5_addr}:${s5_port} check inter 200ms rise 1 fall 1
 
-    backend be6_ws
-        log ${S6_addr}:${S6_port} len 2048 local0
-        http-check send meth GET uri / ver HTTP/1.1 hdr host ws-host hdr connection upgrade hdr upgrade raw-proto
-        http-check expect status 101
-        server srv ${s6_addr}:${s6_port} check inter 200ms rise 1 fall 1
-
 } -start
 
 syslog S1 -wait
@@ -165,4 +138,3 @@
 syslog S3 -wait
 syslog S4 -wait
 syslog S5 -wait
-syslog S6 -wait