This reverts commit f8f43873.

Because this class has some subtle behaviour with regards to control of
exit timing and when and how it streams data to stderr and stdout, it's
worth adding unit tests for this class directly, as well as (in a
followup patch) for FakeProcessManager.

This is additional testing relating to refactoring landed in:
https://github.com/flutter/flutter/pull/103947

Issue: https://github.com/flutter/flutter/issues/102451

* e0f736dab Set error handler (flutter/engine#33402)

* dcd596a99 Roll Dart SDK from 381855557df2 to f3bf9025c141 (1 revision) (flutter/engine#33411)

* 5c2a16e07 Roll Fuchsia Linux SDK from F0_B8WVKY... to IZ7_b83xC... (flutter/engine#33415)

* 4958a245a Roll dart sdk to 1bdb83bddf96c41cc046810c697a2c80bfaaaf19 (flutter/engine#33416)

* d2fd3d852 Roll Fuchsia Mac SDK from t_ky8l6nb... to egBfZMmTP... (flutter/engine#33417)

* d58fc83f1 Roll Dart SDK from 1bdb83bddf96 to 0bc104c3e959 (1 revision) (flutter/engine#33419)

* 8ab172029 Roll Skia from 0a5146ca3ffd to 16fa353926b8 (28 revisions) (flutter/engine#33420)

* Remove fraction translation

* Update codesign.dart
Co-authored-by: Jonah Williams <jonahwilliams@google.com>