Revert "assistant: add PRESUBMIT.py"

This reverts commit 05a4a7f3ac0f5c58d2941d1124bbda87b1bee1fa.

Reason for revert: chrome infra team does not want to do it this way.
Bug: 932269

Original change's description:
> assistant: add PRESUBMIT.py
> 
> Add logic to automatically append chromeos-chrome trybot for
> assistant changes.
> 
> CQ_INCLUDE_TRYBOTS=luci.chrome.try:linux-chromeos-chrome
> 
> Bug: None
> Test: locally run
> Change-Id: I284d888531782f6eaec204337c8ecf5d2903d3f0
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1548134
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Commit-Queue: Xiaohui Chen <xiaohuic@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#646859}

TBR=xiyuan@chromium.org,xiaohuic@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: None
Change-Id: I1643a4332bb6eb845e6b125290a5665835a1e715
Cq-Include-Trybots: luci.chrome.try:linux-chromeos-chrome
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582883
Reviewed-by: Xiaohui Chen <xiaohuic@chromium.org>
Commit-Queue: Xiaohui Chen <xiaohuic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653872}
1 file changed