Merge bitcoin/bitcoin#25161: rpc: Put undocumented JSON failure mode behind a runtime flag

b953ea6cc6 rpc: Put undocumented JSON failure mode behind a runtime flag (Suhail Saqan)

Pull request description:

  Fixes #24695 (Put undocumented JSON failure mode behind a runtime flag)

ACKs for top commit:
  luke-jr:
    utACK b953ea6cc6
  vincenzopalazzo:
    ACK https://github.com/bitcoin/bitcoin/pull/25161/commits/b953ea6cc691ba61bf08eb186e76e7e8b7ba8120

Tree-SHA512: 2005ee1b1f3b637918390b2ecd4166f2fd8c86e3c59fba3da8a0cbd5b1dffd03190c92f6dca3c489ecce4276eaf3108b2edcf9cd6224b713adb52f5bb848163b

test/functional/test_framework/util.py

@@ -378,6 +378,7 @@ def write_config(config_path, *, n, chain, extra_config="", disable_autoconnect=
             f.write("[{}]\n".format(chain_name_conf_section))
         f.write("port=" + str(p2p_port(n)) + "\n")
         f.write("rpcport=" + str(rpc_port(n)) + "\n")
+        f.write("rpcdoccheck=1\n")
         f.write("fallbackfee=0.0002\n")
         f.write("server=1\n")
         f.write("keypool=1\n")