[Tooling] Call use-bot-for-git script directly

[iangmaia]

Given use-bot-for-git already sets up the Git user according to the bot, we can remove this setup from here.

[dangermattic]

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[wpmobilebot]

📲 You can test the changes from this Pull Request in Simplenote Prototype Build by scanning the QR code below to install the corresponding build.

	App Name	Simplenote Prototype Build
	Build Number	pr1679-91e5ced-0192e009-3490-425b-8ccd-dece88caa676
	Version	4.55
	Bundle ID	com.codality.NotationalFlow.Alpha
	Commit	91e5ced
	App Center Build	Simplenote - Installable Builds #405

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[mokagio]

Thanks @iangmaia

I've left a formatting nitpick, Git vs git, which I'll apply. I'll also merge this into release/4.55 so we can test it tomorrow as part of the release finalization