fix(windows): correct git-lfs installation and bump of its version to 3.4.1

[lemeurherve]

Same as jenkinsci/docker-agent#503, this PR mainly add git to the PATH before running git-lfs.exe install instead of git lfs install and unzip git-lfs archive to the correct location to avoir the error git: 'lfs' is not a git command. encountered when bumping git-lfs to its 3.4.1 version, cf #277 (comment)

Other notable changes:

• test added to check if git-lfs (and thus git) is installed and in the PATH
• trimprefix added to the git-lfs source in the corresponding updatecli manifest, easier to work with in files operations and in test

Testing done

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[lemeurherve]

Will probably need #292 & #302

[MarkEWaite]

Are these changes are needed in the proposed upgrade to 3.5.1 as well?

• Bump git-lfs version on Windows to v3.5.1 #366

[lemeurherve]

Are these changes are needed in the proposed upgrade to 3.5.1 as well?

• Bump git-lfs version on Windows to v3.5.1 #366

I think so, I need to check that.

[lemeurherve]

updatecli is failing as one of its targets isn't in the primary branch yet.

[lemeurherve]

From https://ci.jenkins.io/job/Packaging/job/docker-ssh-agent/job/PR-318/21/console

00:05:07.923 Git LFS initialized.

🥳

Tests are still failing, but that's another issue (#292)