mark firebase test lab test flaky because of upstream infra issues (#115178)

Author: christopherfujino

.ci.yaml

@@ -349,6 +349,7 @@ targets:
 
   - name: Linux firebase_release_smoke_test
     recipe: firebaselab/firebaselab
+    bringup: true # https://github.com/flutter/flutter/issues/115170
     timeout: 60
     properties:
       dependencies: >-