Try to bypass the false-positive clang thread analysis warning

This is identical to 70221 except for 3 lines inside SkFlexibleTaskGroup2D::work
to bypass the false-positive warning. We cannot reproduce the error the android
roller generated so we'll have to try and see.

The detailed warning can be found in:
https://skia-review.googlesource.com/c/skia/+/78720

TBR: mtklein@google.com
Bug: skia:
Change-Id: I3e2f414581dbd1398482cf45cf4f43eaf0535651
Reviewed-on: https://skia-review.googlesource.com/79321
Commit-Queue: Yuqian Li <liyuqian@google.com>
Reviewed-by: Yuqian Li <liyuqian@google.com>
5 files changed