Bug 1737673 - Stop setting 'run-on-projects' in variants.yml, r=jmaher

This makes things less confusing as we no longer sneakily override the value
defined in the test configs.

Differential Revision: https://phabricator.services.mozilla.com/D129832

taskcluster/ci/test/misc.yml

@@ -17,6 +17,7 @@ geckoview-junit:
     max-run-time: 3600
     run-on-projects:
         by-variant:
+            geckoview-e10s-single: ['trunk']
             geckoview-fission: ['trunk']
             default: built-projects
     tier: default

taskcluster/ci/test/mochitest.yml

@@ -185,7 +185,10 @@ mochitest-browser-chrome:
                     linux.*64-devedition-qr/opt: built-projects
                     windows10-64-2004-qr/debug: built-projects
                     default: []
-            webrender-sw-a11y-checks: []  # run-on-projects defined in variant config
+            webrender-sw-a11y-checks:
+                by-test-platform:
+                    linux.*64(-shippable)?-qr/opt: ['trunk']
+                    default: []
             webrender-sw-fission:
                 by-test-platform:
                     linux.*64(-asan|-shippable)?-qr/(opt|debug): ['trunk']
@@ -396,7 +399,7 @@ mochitest-devtools-chrome:
         by-variant:
             a11y-checks:
                 by-test-platform:
-                    linux.*64(-shippable)?-qr/opt: built-projects
+                    linux.*64(-shippable)?-qr/opt: ['trunk']
                     default: []
             fission:
                 by-test-platform:

taskcluster/ci/test/variants.yml

@@ -3,11 +3,6 @@ a11y-checks:
     description: "{description} with accessibility checks enabled"
     suffix: "a11y-checks"
     replace:
-        run-on-projects:
-            by-test-platform:
-                linux.*64(-shippable)?-qr/opt:
-                    - "trunk"
-                default: []
         tier: 2
     merge:
         mozharness:
@@ -28,9 +23,6 @@ geckoview-e10s-single:
     description: "{description} with single-process e10s"
     when:
         <<: *gv_e10s_filter
-    replace:
-        run-on-projects:
-            - "trunk"
     suffix: "e10s-single"
     merge:
         mozharness:
@@ -127,11 +119,6 @@ webrender-sw-a11y-checks:
     description: "{description} with software webrender and accessibility checks enabled"
     suffix: "swr-a11y-checks"
     replace:
-        run-on-projects:
-            by-test-platform:
-                linux.*64(-shippable)?-qr/opt:
-                    - "trunk"
-                default: []
         tier: 2
     merge:
         webrender: true