Bug 1677759: Disable TCP in these tests to ensure that UDP srflx/relay are working. r=mjf

This was what ended up finding this bug.

Differential Revision: https://phabricator.services.mozilla.com/D97635

dom/media/webrtc/tests/mochitests/test_peerConnection_basicAudioNATRelay.html

@@ -9,7 +9,7 @@
 <script type="application/javascript">
 createHTML({
   bug: "1231975",
-  title: "Basic audio-only peer connection with port dependent NAT"
+  title: "Basic audio-only peer connection with port dependent NAT, for verifying UDP relay"
 });
 
 // This test uses the NAT simulator, which doesn't work in https, so we turn
@@ -23,6 +23,7 @@ if (!("mediaDevices" in navigator)) {
         ['media.peerconnection.ice.obfuscate_host_addresses', false],
         ['media.peerconnection.nat_simulator.filtering_type', 'PORT_DEPENDENT'],
         ['media.peerconnection.nat_simulator.mapping_type', 'PORT_DEPENDENT'],
+        ['media.peerconnection.nat_simulator.block_tcp', true],
         ['media.getusermedia.insecure.enabled', true]);
     options.expectedLocalCandidateType = "srflx";
     options.expectedRemoteCandidateType = "relay";

dom/media/webrtc/tests/mochitests/test_peerConnection_basicAudioNATSrflx.html

@@ -9,7 +9,7 @@
 <script type="application/javascript">
 createHTML({
   bug: "1231975",
-  title: "Basic audio-only peer connection with endpoint independent NAT"
+  title: "Basic audio-only peer connection with endpoint independent NAT, for verifying UDP srflx"
 });
 
 // This test uses the NAT simulator, which doesn't work in https, so we turn
@@ -23,6 +23,7 @@ if (!("mediaDevices" in navigator)) {
         ['media.peerconnection.ice.obfuscate_host_addresses', false],
         ['media.peerconnection.nat_simulator.filtering_type', 'ENDPOINT_INDEPENDENT'],
         ['media.peerconnection.nat_simulator.mapping_type', 'ENDPOINT_INDEPENDENT'],
+        ['media.peerconnection.nat_simulator.block_tcp', true],
         ['media.getusermedia.insecure.enabled', true]);
     options.expectedLocalCandidateType = "srflx";
     options.expectedRemoteCandidateType = "srflx";