REGTESTS: fix http_reuse_conn_hash proxy test

Define pool-low-conn to 2 to force to have at least 2 idle connections
on the server side for the purpose of the test.
diff --git a/reg-tests/connection/http_reuse_conn_hash.vtc b/reg-tests/connection/http_reuse_conn_hash.vtc
index 58118d2..f6c8765 100644
--- a/reg-tests/connection/http_reuse_conn_hash.vtc
+++ b/reg-tests/connection/http_reuse_conn_hash.vtc
@@ -26,7 +26,7 @@
 	listen sender-proxy
 		bind "fd@${feS_proxy}" accept-proxy
 		http-reuse always
-		server srv2 ${h1_feR_proxy_addr}:${h1_feR_proxy_port} send-proxy
+		server srv2 ${h1_feR_proxy_addr}:${h1_feR_proxy_port} send-proxy pool-low-conn 2
 
 	listen receiver
 		bind "fd@${feR_ssl}" ssl crt ${testdir}/common.pem
@@ -146,9 +146,8 @@
 	expect resp.status == 200
 	expect resp.http.http_first_request == "0"
 
-	# TODO this test does not pass on the CI
-	#txreq
-	#rxresp
-	#expect resp.status == 200
-	#expect resp.http.http_first_request == "0"
+	txreq
+	rxresp
+	expect resp.status == 200
+	expect resp.http.http_first_request == "0"
 } -run