Mark the embedded_android_views_test as non flaky. (#20962)

Was marked as flaky as that's our policy for assing new device lab
tests. It's been consistently green so marking as non flaky.

dev/devicelab/manifest.yaml

@@ -135,7 +135,6 @@ tasks:
       Tests embedded Android views.
     stage: devicelab
     required_agent_capabilities: ["mac/android"]
-    flaky: true
 
   run_release_test:
     description: >