Enable android_preview_tool_integration_tests check (flutter#140470)

Enables the check that was added in flutter#131901.

Has been passing since flutter#140099 (30 runs). Not sure what the normal number of successful runs we wait for is before enabling, let me know if we should wait for more data.

Author: gmackall

.ci.yaml

@@ -1064,7 +1064,6 @@ targets:
       - .ci.yaml
 
   - name: Linux android_preview_tool_integration_tests
-    bringup: true
     recipe: flutter/flutter_drone
     timeout: 60
     properties: