Ensure depot_tools is in path when building and checking out code. This is to prevent errors when goma and recipes do not find vpython. Change-Id: I098e35a52e9ac0410bb4d2f8911973a3a520fbc1 Bugs: https://github.com/flutter/flutter/issues/63212 https://github.com/flutter/flutter/issues/63100 Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/6080 Reviewed-by: Tong Wu <wutong@google.com> Reviewed-by: Christopher Fujino <fujino@google.com> Commit-Queue: Godofredo Contreras <godofredoc@google.com>