Use git exec candidate list on all platforms for build

[mtolmacs]

build/git_revision.py now uses a git executable name search list on all platforms, avoiding issues with some Windows installations.

Linked issues

• Fixes Engine configuration phase on Windows cannot find git.bat in git_revision.py with some git installations flutter#106615

Impact on flutter/tests repo

This PR does not affect the flutter/tests repo.

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide and the C++, Objective-C, Java style guides.
• I listed at least one issue that this PR fixes in the description above.
• I added new tests to check the change I am making or feature I am adding, or Hixie said the PR is test-exempt. See testing the engine for instructions on writing and running engine tests.
• I updated/added relevant documentation (doc comments with ///).
• I signed the CLA.
• All existing and new tests are passing.

[zanderso]

Is a similar fix also needed in tools/githooks/setup.py?

[mtolmacs]

@zanderso you're correct, I wasn't sure whether that fix is relevant to the topic (i.e. build on windows). Anyway I added the modification to setup.py as well.