Do not fail the build if adb, dart, etc process do not exist.

Builds are failing because we try to kill windows processes at the end
of the task execution. This is expected and we should avoid failing the
full task when that happens.

Change-Id: I681179cf255069e3f9a24536d527c68d8034ec96
Bug: https://github.com/flutter/flutter/issues/63699
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/5623
Reviewed-by: Keyong Han <keyonghan@google.com>
Commit-Queue: Godofredo Contreras <godofredoc@google.com>
3 files changed
tree: b2d62881b270253772efc27da3497fa5e88b0be0
  1. infra/
  2. recipe_modules/
  3. recipes/
  4. .gitignore
  5. .style.yapf
  6. OWNERS
  7. recipes.py