REGTESTS: fix maxconn update with agent-check

Correct the typo in the parameter used to update the 'maxconn' via
agent-check. The test is also completed to detect the update of maxconn
using CLI 'show stats'.

(cherry picked from commit e500e593a79e3797eada5a839aeee017b002d7bf)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/reg-tests/checks/agent-check.vtc b/reg-tests/checks/agent-check.vtc
index 1345693..4bab934 100644
--- a/reg-tests/checks/agent-check.vtc
+++ b/reg-tests/checks/agent-check.vtc
@@ -9,7 +9,7 @@
 server s1 {
   barrier b1 sync
   recv 5
-  send "75%,max-conn:30,maint,down\n"
+  send "75%,maxconn:30,maint,down\n"
   expect_close
   barrier b2 sync
 } -start
@@ -31,8 +31,13 @@
 haproxy h1 -cli {
     send "show servers state"
     expect ~ "be1 1 srv 127.0.0.1 2 0 100 100 [[:digit:]]+ 1 0 [[:digit:]] 0 [[:digit:]]+ 0 0 - ${s1_port} -"
+    send "show stat"
+    expect ~ "be1,srv,0,0,0,0,,"
+
     barrier b1 sync
     barrier b2 sync
     send "show servers state"
     expect ~ "be1 1 srv 127.0.0.1 0 1 75 100 [[:digit:]]+ 1 0 [[:digit:]] 0 [[:digit:]]+ 0 0 - ${s1_port} -"
+    send "show stat"
+    expect ~ "be1,srv,0,0,0,0,30"
 }