Add build matrix with Windows and Mac queues for E2E tests

.buildkite/pipeline.yml

@@ -33,7 +33,7 @@ steps:
 
   # FIXME: Tests are currently failing but that's not due to CI
   # See https://github.com/Automattic/studio/issues/37
-  - label: E2E Tests macOS
+  - label: E2E Tests
     key: e2e_tests
     command: |
       .buildkite/commands/install-node-dependencies.sh
@@ -42,6 +42,13 @@ steps:
       echo '--- :playwright: Run End 2 End Tests'
       npm run e2e
     plugins: *common_plugins
+    agents:
+      queue: {{ matrix.queue }}
+    matrix:
+      setup:
+        queue:
+          - mac
+          - windows
 
   - label: '🔨 Create Dev Build'
     key: 'dev'