Linux flutter_gallery_sksl_warmup__transition_perf is 6.76% flaky

[flutterflakybot]

The post-submit test builder Linux flutter_gallery_sksl_warmup__transition_perf had a flaky ratio 6.76% for the past 15 days, which is above our 2.00% threshold.

One recent flaky example for a same commit: https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2105
Commit: flutter@9c32e5a
Flaky builds:
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2107
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2105
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2088
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2087
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2074
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2072

Succeeded builds (3 most recent):
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2109
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2108
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery_sksl_warmup__transition_perf/2106

Please follow https://github.com/flutter/flutter/wiki/Reducing-Test-Flakiness#fixing-flaky-tests to fix the flakiness and enable the test back after validating the fix (internal dashboard to validate: go/flutter_test_flakiness).