Bug 1641328 - disable test_memory_usage.py on win fission r=sparky

Differential Revision: https://phabricator.services.mozilla.com/D84830

taskcluster/ci/test/awsy.yml

@@ -46,7 +46,10 @@ awsy:
 
 awsy-tp6:
     description: "Are we slim yet - tp6 pageset"
-    variants: ["fission"]
+    variants: 
+        by-test-platform:
+            windows10-64-shippable-qr/opt: [] # temporary disable on win
+            default: ['fission']
     treeherder-symbol: SY(sy-tp6)
     run-on-projects:
         by-test-platform: