[GTK][GStreamer] REGRESSION(303623@main) webrtc/ephemeral-certificates-and-cnames.html is timing out

[philn]

da9228ebec2c38bcf54b025ff040fb08a2057363

[GTK][GStreamer] REGRESSION(303623@main) webrtc/ephemeral-certificates-and-cnames.html is timing out
https://bugs.webkit.org/show_bug.cgi?id=304065

Reviewed by NOBODY (OOPS!).

The timeout was actually a crash, the mediastreamsrc element being disposed from a non-main thread.

Driving-by, set a 3 seconds timeout for the RiceBackend::GatherSocketAddresses sync IPC, and unflag
webrtc/datachannel/multiple-connections.html now that bug 303366 is fixed.

* LayoutTests/platform/gtk/TestExpectations:
* Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp:
(WebCore::GStreamerMediaEndpoint::prepareForClose):
(WebCore::GStreamerMediaEndpoint::close):
* Source/WebCore/platform/mediastream/gstreamer/RealtimeOutgoingMediaSourceGStreamer.cpp:
(WebCore::RealtimeOutgoingMediaSourceGStreamer::stopOutgoingSource):
* Source/WebKit/WebProcess/Network/webrtc/rice/RiceBackendProxy.cpp:
(WebKit::RiceBackendProxy::gatherSocketAddresses):

https://github.com/WebKit/WebKit/commit/da9228ebec2c38bcf54b025ff040fb08a2057363

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 api-mac-debug	✅ 🛠 wpe-cairo-libwebrtc
	✅ 🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv-sim	✅ 🛠 mac-safer-cpp
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash https://github.com/WebKit/WebKit/commit/da9228ebec2c38bcf54b025ff040fb08a2057363)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	⏳ 🧪 win-tests
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 api-mac-debug	✅ 🛠 wpe-cairo-libwebrtc
	✅ 🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
	✅ 🧪 vision-wk2	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv-sim	✅ 🛠 mac-safer-cpp
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash https://github.com/WebKit/WebKit/commit/9351017676d57b20e4f4a9bfe01669e89d8676cc)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 win
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	~~🧪 win-tests~~
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 api-mac-debug	✅ 🛠 wpe-cairo-libwebrtc
	✅ 🧪 api-ios	✅ 🧪 mac-wk1	✅ 🛠 gtk
	✅ 🛠 vision	✅ 🧪 mac-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	✅ 🧪 mac-wk2-stress	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🧪 mac-intel-wk2
	✅ 🛠 tv-sim	✅ 🛠 mac-safer-cpp
	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 304446@main (14447d29ae4f): https://commits.webkit.org/304446@main

Reviewed commits have been landed. Closing PR #55309 and removing active labels.