MINOR: contrib/prometheus-exporter: avoid connection close header

it does not seem to have a reason to close connections after each
request; reflect that in tests by doing all requests within the same
client.

Signed-off-by: William Dauchy <wdauchy@gmail.com>
(cherry picked from commit 1704efee89c9a0d430e63e7a9b54e97644d27a2a)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/contrib/prometheus-exporter/service-prometheus.c b/contrib/prometheus-exporter/service-prometheus.c
index bb728a8..0871501 100644
--- a/contrib/prometheus-exporter/service-prometheus.c
+++ b/contrib/prometheus-exporter/service-prometheus.c
@@ -2459,7 +2459,6 @@
 		goto full;
 	sl->info.res.status = 200;
 	if (!htx_add_header(htx, ist("Cache-Control"), ist("no-cache")) ||
-	    !htx_add_header(htx, ist("Connection"), ist("close")) ||
 	    !htx_add_header(htx, ist("Content-Type"), ist("text/plain; version=0.0.4")) ||
 	    !htx_add_header(htx, ist("Transfer-Encoding"), ist("chunked")) ||
 	    !htx_add_endof(htx, HTX_BLK_EOH))
diff --git a/reg-tests/contrib/prometheus.vtc b/reg-tests/contrib/prometheus.vtc
index 64b9cc0..59ff82d 100644
--- a/reg-tests/contrib/prometheus.vtc
+++ b/reg-tests/contrib/prometheus.vtc
@@ -37,22 +37,12 @@
 	expect resp.body ~ ".*haproxy_frontend.*"
 	expect resp.body ~ ".*haproxy_backend.*"
 	expect resp.body ~ ".*haproxy_server.*"
-} -run
 
-client c2 -connect ${h1_stats_sock} {
-	txreq -url "/metrics?scope"
-	rxresp
-	expect resp.status == 400
-} -run
-
-client c3 -connect ${h1_stats_sock} {
 	txreq -url "/metrics?scope="
 	rxresp
 	expect resp.status == 200
 	expect resp.bodylen == 0
-} -run
 
-client c4 -connect ${h1_stats_sock} {
 	txreq -url "/metrics?scope=server"
 	rxresp
 	expect resp.status == 200
@@ -60,9 +50,7 @@
 	expect resp.body !~ ".*haproxy_frontend.*"
 	expect resp.body !~ ".*haproxy_backend.*"
 	expect resp.body ~ ".*haproxy_server.*"
-} -run
 
-client c5 -connect ${h1_stats_sock} {
 	txreq -url "/metrics?scope=frontend&scope=backend"
 	rxresp
 	expect resp.status == 200
@@ -70,4 +58,8 @@
 	expect resp.body ~ ".*haproxy_frontend.*"
 	expect resp.body ~ ".*haproxy_backend.*"
 	expect resp.body !~ ".*haproxy_server.*"
+
+	txreq -url "/metrics?scope"
+	rxresp
+	expect resp.status == 400
 } -run