PRESUBMIT.py: remove `USE_PYTHON3 = True`

presubmit now uses python3 only.

This is generated by
$ rg -l '^USE_PYTHON3 = True' | \
  xargs sed -z -i "s/\n*USE_PYTHON3 = True\n*/\n\n/"
with some more modifications.

This also removes run_on_python2, run_on_python3, and skip_shebang_check
args.

Bug: 1207012
Change-Id: I8c842d0a9ac485a27399d704a17b755f58a64db8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4573952
Reviewed-by: Nico Weber <thakis@chromium.org>
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Owners-Override: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1152319}
NOKEYCHECK=True
GitOrigin-RevId: 40def4845583973fe2301dc7829b4ee39c92b617
1 file changed
tree: 3243032278b460b8a3c7bbc03710ad28e107a307
  1. development/
  2. DIR_METADATA
  3. LICENSE
  4. OWNERS
  5. README.chromium