[GStreamer][WebCodecs] AV1 (with dav1d) decoding fixes

[philn]

f3b3ddc

[GStreamer][WebCodecs] AV1 (with dav1d) decoding fixes
https://bugs.webkit.org/show_bug.cgi?id=272642

Reviewed by Xabier Rodriguez-Calvar.

The decoder tests were failing mostly due to incomplete colorimetry handling in dav1ddec, which was
fixed upstream. The low-latency decoding test was failing because we were not configuring the
decoder to internally use a single thread. The parser was discarding corrupted frames, leading to
another test failure, so it was removed from the harnessed pipeline (the decoder rejects corrupted
frames already).

* LayoutTests/platform/glib/TestExpectations:
* LayoutTests/platform/glib/imported/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any.worker_av1-expected.txt: Removed.
* LayoutTests/platform/glib/imported/w3c/web-platform-tests/webcodecs/full-cycle-test.https.any_av1-expected.txt: Removed.
* Source/WebCore/platform/graphics/gstreamer/GStreamerCommon.cpp:
(WebCore::configureVideoDecoderForHarnessing):
* Source/WebCore/platform/graphics/gstreamer/VideoDecoderGStreamer.cpp:
(WebCore::GStreamerInternalVideoDecoder::GStreamerInternalVideoDecoder):

Canonical link: https://commits.webkit.org/277488@main

7d5a0d1

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-skia
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim		✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 7d5a0d1)

Misc	iOS, tvOS & watchOS	macOS	Linux	Windows
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	✅ 🛠 wincairo
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe
	✅ 🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-skia
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 tv	✅ 🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 tv-sim		✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 277488@main (f3b3ddc): https://commits.webkit.org/277488@main

Reviewed commits have been landed. Closing PR #27230 and removing active labels.