Bug 1733631 - [ci] Stop keying 'mochitest-browser-chrome-failures' variants by-platform, r=jmaher

Differential Revision: https://phabricator.services.mozilla.com/D128834

taskcluster/ci/config.yml

@@ -65,6 +65,7 @@ treeherder:
         'M-f-spi-nw-1proc': 'Mochitest failures with networking on socket process without e10s'
         'M-f-swr': 'Mochitests failures with software webrender enabled'
         'M-f-swr-1proc': 'Mochitests failures with software webrender enabled without e10s'
+        'M-f-wayland': 'Mochitests failures with Wayland backend enabled'
         'MSI': 'Repack installers into MSIs'
         'MSIs': 'Signing of Repacked installers of MSIs'
         'MSIX': 'Repack into MSIX package'

taskcluster/ci/test/mochitest.yml

@@ -249,12 +249,26 @@ mochitest-browser-chrome-failures:
     max-run-time: 2700
     e10s: true
     variants:
-        by-test-platform:
-            linux.*64/debug: ['fission', 'wayland', 'socketprocess_networking']
-            linux.*64-qr/debug: ['webrender-sw', 'fission', 'wayland', 'socketprocess_networking']
-            android-em-7.0-x86_64-qr/debug: ['webrender-sw', 'fission']
-            default: ['fission']
-    run-on-projects: ['mozilla-central']
+        - fission
+        - socketprocess_networking
+        - wayland
+        - webrender-sw
+    run-on-projects:
+        by-variant:
+            socketprocess_networking:
+                by-test-platform:
+                    linux.*64-qr/debug: built-projects
+                    default: []
+            wayland:
+                by-test-platform:
+                    linux.*64-qr/debug: built-projects
+                    default: []
+            webrender-sw:
+                by-test-platform:
+                    android-em-7.0-x86_64-qr/debug: built-projects
+                    linux.*64-qr/debug: built-projects
+                    default: []
+            default: ['mozilla-central']
     mozharness:
         mochitest-flavor: browser
         chunked: true