Bug 1546610 - reduce marionette-headless to run on linux64/shippable as tier2 only. r=whimboo

reduce marionette-headless to run on linux64/shippable as tier2 only

Differential Revision: https://phabricator.services.mozilla.com/D28838

--HG--
extra : moz-landing-system : lando

taskcluster/ci/test/marionette.yml

@@ -39,6 +39,7 @@ marionette-headless:
     treeherder-symbol: MnH
     max-run-time: 5400
     instance-size: default
+    tier: 2
     mozharness:
         extra-options:
             - --headless

taskcluster/ci/test/test-platforms.yml

@@ -60,6 +60,7 @@ linux64-shippable/opt:
         - talos
         - awsy
         - mochitest-headless
+        - marionette-headless
         - linux-talos-flex
         - raptor-chromium
         - raptor-fetch-chromium

taskcluster/ci/test/test-sets.yml

@@ -24,7 +24,6 @@ common-tests:
     - jittest
     - jsreftest
     - marionette
-    - marionette-headless
     - mochitest
     - mochitest-a11y
     - mochitest-browser-chrome
@@ -232,7 +231,6 @@ windows-tests:
     - jittest
     - jsreftest
     - marionette
-    - marionette-headless
     - mochitest
     - mochitest-a11y
     - mochitest-browser-chrome
@@ -259,7 +257,6 @@ windows-aarch64-tests:
     - jittest
     - jsreftest
     - marionette
-    - marionette-headless
     - mochitest
     - mochitest-a11y
     - mochitest-browser-chrome
@@ -310,7 +307,6 @@ macosx64-tests:
     - jittest
     - jsreftest
     - marionette
-    - marionette-headless
     - mochitest
     - mochitest-a11y
     - mochitest-browser-chrome
@@ -439,6 +435,9 @@ devtools-tests:
 mochitest-headless:
     - mochitest-plain-headless
 
+marionette-headless:
+    - marionette-headless
+
 android-hw-arm7-opt-unittests:
     - jittest
     - mochitest-media