Bug 1689554 - Enable UDPSocket on the socket process and fix a test r=necko-reviewers,kershaw

Differential Revision: https://phabricator.services.mozilla.com/D106506

netwerk/build/components.conf

@@ -460,6 +460,7 @@ Classes = [
         'contract_ids': ['@mozilla.org/network/udp-socket;1'],
         'type': 'mozilla::net::nsUDPSocket',
         'headers': ['/netwerk/base/nsUDPSocket.h'],
+        'processes': ProcessSelector.ALLOW_IN_SOCKET_PROCESS,
     },
     {
         'cid': '{ff41913b-546a-4bff-9201-dc9b2c032eba}',

netwerk/test/unit/test_trr_https_fallback.js

@@ -673,6 +673,11 @@ add_task(async function testH3Connection() {
   );
   Services.prefs.setBoolPref("network.http.http3.enabled", true);
 
+  Services.prefs.setIntPref(
+    "network.dns.httpssvc.http3_fast_fallback_timeout",
+    100
+  );
+
   await trrServer.registerDoHAnswers("test.h3.com", "HTTPS", [
     {
       name: "test.h3.com",