PLT-6358: Server HTTP client improvements (#6980)

* restrict untrusted, internal http connections by default

* command test fix

* more test fixes

* change setting from toggle to whitelist

* requested ui changes

* add isdefault diagnostic

* fix tests

config/config.json

@@ -27,6 +27,7 @@
         "EnableDeveloper": false,
         "EnableSecurityFixAlert": true,
         "EnableInsecureOutgoingConnections": false,
+        "AllowedUntrustedInternalConnections": "",
         "EnableMultifactorAuthentication": false,
         "EnforceMultifactorAuthentication": false,
         "EnableUserAccessTokens": false,