cull_opacity_perf__timeline_summary timing out

cull_opacity_perf__timeline_summary started timing out with https://github.com/flutter/flutter/pull/65044, but the [revert](https://github.com/flutter/flutter/commit/ea75ffc1ba8a0af33bdba352e733c2ba5fa11472) didn't fix it.
[cull_opacity_perf__timeline_summary_48ba488_2.log](https://github.com/flutter/flutter/files/5240887/cull_opacity_perf__timeline_summary_48ba488_2.log)
