githooks: enter the chroot in presubmits

In general, running tests is likely best done in a consistent
environment. The more pressing concern here is that depot_tools doesn't
fully support python3 yet, so things like our `yapf` check always fail
outside of the chroot, if they happen to pick up on depot_tools' yapf.

BUG=chromium:1030828
TEST=Ran presubmits on files with type annotations. They now work inside
     or outside of the chroot.

Change-Id: If22a3766e01ea26ebc9e78bc4b40d90ad5d49049
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/2182163
Reviewed-by: Tiancong Wang <tcwang@google.com>
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Tested-by: George Burgess <gbiv@chromium.org>
1 file changed