[vm/concurrency] Remove file_write_as_test from iso-stress test suite.
[vm/concurrency] Remove file_write_as_test from iso-stress test suite.

The test seems to be hanging, remove it to green the bot.

BUG=https://github.com/dart-lang/sdk/issues/46694
TEST=iso-stress test bot

Change-Id: I4b1f27354208f24395d41bfca0403cbabdb4ce35
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/207922
Reviewed-by: Alexander Aprelev <dfb74c35a357c2059971a4bf7fe26b6a7c18085d@google.com>
Commit-Queue: Alexander Aprelev <dfb74c35a357c2059971a4bf7fe26b6a7c18085d@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk