Reland "Reland "Use bundled python to run gn""

This reverts commit 6678906cf890fea0ba6d7f8e5f553d230c014f43.

Reason for revert:
run gn.py instead of gn on PATH in presubmit check.

Bug: 414312048
Original change's description:
> Revert "Reland "Use bundled python to run gn""
>
> This reverts commit 49fcbee29e78d9307f37037223dcc99b0bc7df8a.
>
> Reason for revert: This broke a presubmit check in devtools-frontend https://ci.chromium.org/ui/p/devtools-frontend/builders/try/dtf_presubmit_linux/b8715987965894722097/overview
>
> Bug: 414312048
> Original change's description:
> > Reland "Use bundled python to run gn"
> >
> > This reverts commit a3cdfed6c4f175036560721de6f8b90bc658d09a.
> >
> > Reason for revert:
> > https://chromium-review.googlesource.com/c/chromium/src/+/6498495 landed
> >
> > Original change's description:
> > > Revert "Use bundled python to run gn"
> > >
> > > This reverts commit fa8fc854e1766b86f10c9a15902cf3cc23adaac2.
> > >
> > > Reason for revert: Most likely culprit for consistent failure
> > > to generate orderfiles (see crbug.com/414312048).
> > >
> > > Bug: 414312048
> > >
> > > Original change's description:
> > > > Use bundled python to run gn
> > > >
> > > > Change-Id: If01a7dae1aca72c93c87c1db27d2d37432094852
> > > > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6490515
> > > > Reviewed-by: Junji Watanabe <jwata@google.com>
> > > > Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
> > > > Auto-Submit: Fumitoshi Ukai <ukai@google.com>
> > > > Commit-Queue: Fumitoshi Ukai <ukai@google.com>
> > >
> > > No-Presubmit: true
> > > No-Tree-Checks: true
> > > No-Try: true
> > > Change-Id: Id5e5f7cec91927aae144026aa16b169689881fb2
> > > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6494846
> > > Owners-Override: Friedrich Hauser <friedrichh@chromium.org>
> > > Auto-Submit: Friedrich Hauser <friedrichh@chromium.org>
> > > Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> > > Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> >
> > Bug: 414312048
> > Change-Id: Id04cfe67ed994b91d794e51ba329f411de5d2d36
> > Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6504176
> > Commit-Queue: Fumitoshi Ukai <ukai@google.com>
> > Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
> > Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
> > Reviewed-by: Junji Watanabe <jwata@google.com>
>
> Bug: 414312048
> Change-Id: Iadb3bd20af737c1e7404bf8e95c333f1dbd62942
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6508888
> Commit-Queue: Garrett Beaty <gbeaty@google.com>
> Reviewed-by: Garrett Beaty <gbeaty@google.com>
> Owners-Override: Garrett Beaty <gbeaty@google.com>
> Auto-Submit: Liviu Rau <liviurau@chromium.org>
> Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>

Bug: 414312048
Change-Id: I86d611b234bd5b2e91b184c7610c18cfe79f9816
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6515221
Reviewed-by: Junji Watanabe <jwata@google.com>
Auto-Submit: Fumitoshi Ukai <ukai@google.com>
Commit-Queue: Gavin Mak <gavinmak@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>

gn

@@ -11,4 +11,4 @@ if [ "$(expr "$(uname -s)" : "^MINGW64_NT")" == "10" ]; then
     exit
 fi
 
-PYTHONDONTWRITEBYTECODE=1 exec python3 "$base_dir/gn.py" "$@"
+PYTHONDONTWRITEBYTECODE=1 "$base_dir/python-bin/python3" "$base_dir/gn.py" "$@"

gn.bat

@@ -8,5 +8,7 @@ setlocal
 :: standalone, but allow other PATH manipulations to take priority.
 set PATH=%PATH%;%~dp0
 
+set scriptdir=%~dp0
+
 :: Defer control.
-python3 "%~dp0\gn.py" %*
+@call %scriptdir%python-bin\python3 "%~dp0\gn.py" %*

presubmit_canned_checks.py

@@ -1876,7 +1876,11 @@ def CheckGNFormatted(input_api, output_api):
         ).endswith('.gni') or x.LocalPath().endswith('.typemap'))
     warnings = []
     for f in affected_files:
-        cmd = ['gn', 'format', '--dry-run', f.AbsoluteLocalPath()]
+        cmd = [
+            input_api.python3_executable,
+            input_api.os_path.join(_HERE, 'gn.py'), 'format', '--dry-run',
+            f.AbsoluteLocalPath()
+        ]
         rc = gn.main(cmd)
         if rc == 2:
             warnings.append(