webrtc/connection-state.html started failing after update to 1.24.0 https://bugs.webkit.org/show_bug.cgi?id=271243 <rdar://problem/125014192>

Reviewed by Xabier Rodriguez-Calvar.

The `doneGatheringCandidates()` method is called by the PeerConnectionBackend when it's notified
from gst-webrtc that the ICE gathering is finished, so we don't need to call it ourselves. The
end-of-candidates SDP attribute shouldn't appear in the offer/answer the end-point reports either.
This is covered by the webrtc/libwebrtc/descriptionGetters.html test.

* LayoutTests/platform/glib/TestExpectations:
* Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp:
(WebCore::fetchDescription):
(WebCore::GStreamerMediaEndpoint::doSetLocalDescription):
(WebCore::GStreamerMediaEndpoint::doSetRemoteDescription):
(WebCore::GStreamerMediaEndpoint::onIceCandidate):

Canonical link: https://commits.webkit.org/276412@main

Author: philn

Source/WebCore/Modules/mediastream/gstreamer/GStreamerMediaEndpoint.cpp

@@ -313,7 +313,7 @@ static std::optional<std::pair<RTCSdpType, String>> fetchDescription(GstElement*
         const auto attribute = gst_sdp_message_get_attribute(description->sdp, i);
         if (!g_strcmp0(attribute->key, "end-of-candidates")) {
             gst_sdp_message_remove_attribute(description->sdp, i);
-            i--;
+            break;
         }
     }