[GTK][WPE] Gardening LayoutTests/webrtc/video-disabled-black.html

Unreviewed test gardening.

Test was gardened a couple of weeks ago in webkit.org/b/261024; and
webkit.org/b/254212 is also related to this test as a fix. Since
webkit.org/b/254212, test has been flaky; prior to that, it failed in bots.
Generally a flaky test as noted in 261024 which is still open.

Noted in existing bugs 261024, 254212; moved expectations up to glib.

* LayoutTests/platform/glib/TestExpectations: move expectation here for flakiness
* LayoutTests/platform/gtk/TestExpectations:

Canonical link: https://commits.webkit.org/268498@main

LayoutTests/platform/glib/TestExpectations

@@ -3470,6 +3470,7 @@ webkit.org/b/261024 svg/text/small-fonts-in-html5.html [ Failure ImageOnlyFailur
 webkit.org/b/261024 webrtc/video-maxFramerate.html [ Pass Timeout ]
 webkit.org/b/261024 webrtc/video-replace-muted-track.html [ Pass Timeout ]
 webkit.org/b/261024 webrtc/video-unmute.html [ Pass Timeout ]
+webkit.org/b/261024 webrtc/video-disabled-black.html [ Crash Pass ]
 
 # Initial css/compositing test import
 imported/w3c/web-platform-tests/css/compositing/canvas-composite-modes.html [ ImageOnlyFailure ]

LayoutTests/platform/gtk/TestExpectations

@@ -2657,6 +2657,5 @@ webkit.org/b/261024 webgl/2.0.y/conformance/offscreencanvas/context-attribute-pr
 webkit.org/b/261024 webgl/2.0.y/conformance/renderbuffers/framebuffer-state-restoration.html [ Pass Timeout ]
 webkit.org/b/261024 webgl/2.0.y/conformance/rendering/color-mask-preserved-during-implicit-clears.html [ Pass Timeout ]
 webkit.org/b/261024 webrtc/utf8-sdp.html [ Pass Timeout ]
-webkit.org/b/261024 webrtc/video-disabled-black.html [ Crash Pass ]
 
 imported/w3c/web-platform-tests/css/filter-effects/backdrop-filter-plus-filter.html [ ImageOnlyFailure ]