Mark analyzer_benchmark unflaky (#160991)

This should have been marked unflaky when
flutter/flutter#158243 was closed.

Author: jmagman

.ci.yaml

@@ -362,7 +362,6 @@ targets:
   # are intentionally running it in the devicelab to ensure that it does not
   # run on a VM in order to avoid noisy results from the benchmark.
   - name: Linux analyzer_benchmark
-    bringup: true # Flaky https://github.com/flutter/flutter/issues/158243
     recipe: devicelab/devicelab_drone
     timeout: 60
     properties: