Bring back mkdir call in PushChangedFiles
Bring back mkdir call in PushChangedFiles

https://chromium-review.googlesource.com/c/catapult/+/2170402 removed
the mkdir call as it seemed pointless.

It still seems pointless, but causes breakpad_unittests and
sandbox_linux_unittests only on android-pie-x86-rel to fail test setup.
I can't repro locally to figure out why it fails, so I'm just bringing
back the mkdir call.

Ran chromium tests on
https://chromium-review.googlesource.com/c/chromium/src/+/2210638,
and breakpad_unittests and sandbox_linux_unittests pass.

Bug: chromium:1076580
Change-Id: I58494fba5e5b329ffd789faff14132c21db3f89b
Reviewed-on: https://chromium-review.googlesource.com/c/catapult/+/2208122
Reviewed-by: Ben Pastene <e214258550f76fa23ac7c1d953424f3f468f5c6b@chromium.org>
Commit-Queue: Michael Thiessen <592b72e1cff7dc8c6fa9a145a6d891fe715588c7@chromium.org>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult