[qa]: add parsing for '<host>:<port>' argument form to rpc_url()

Github-Pull: #8400
Rebased-From: 0ff4375c93

qa/rpc-tests/test_framework/util.py

@@ -171,7 +171,15 @@ def rpc_auth_pair(n):
 
 def rpc_url(i, rpchost=None):
     rpc_u, rpc_p = rpc_auth_pair(i)
-    return "http://%s:%s@%s:%d" % (rpc_u, rpc_p, rpchost or '127.0.0.1', rpc_port(i))
+    host = '127.0.0.1'
+    port = rpc_port(i)
+    if rpchost:
+        parts = rpchost.split(':')
+        if len(parts) == 2:
+            host, port = parts
+        else:
+            host = rpchost
+    return "http://%s:%s@%s:%d" % (rpc_u, rpc_p, host, int(port))
 
 def wait_for_bitcoind_start(process, url, i):
     '''