Linux flutter_gallery__transition_perf is 5.13% flaky

[flutterflakybot]

The post-submit test builder Linux flutter_gallery__transition_perf had a flaky ratio 5.13% 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__transition_perf/2182
Commit: flutter@c5573ea
Flaky builds:
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery__transition_perf/2182
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery__transition_perf/2174
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery__transition_perf/2169
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery__transition_perf/2149

Succeeded builds (3 most recent):
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery__transition_perf/2188
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery__transition_perf/2187
https://ci.chromium.org/ui/p/flutter/builders/prod/Linux%20flutter_gallery__transition_perf/2186

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).