🩹 Downgrade git from v2.47.1.windows.1 to v2.47.0.windows.2

[s-weigand]

The version of curl bundled with mingit v2.47.1.windows.1 has a regression where the fallback to ~/_netrc on windows is ignored and it only uses ~/.netrc.
See git-for-windows/git#5306
Since git lfs on windows only supports ~/_netrc we decided to downgrade mingit to the latest working version (I tested that it works).

I created an issue to remind us update mingit.

Change summary

• 🩹 Pin git version in server image to 2.47.0.2
  See the package definition for how the git for windows version translates to the version on winget.
• 🩹 Manually install mingit and git lfs in servercore image
  While the upstream image ghcr.io/s-weigand/mingit:ltsc2022 is now fixed, the ltsc2022 tag is a rolling tag, so having the install commands contained in the Dockerfile is more transparent and gives us more control.
• 🧹 Use / in paths instead of \ (/ is a perfectly fine path separator on window, no need to use \ in places where we don't have to)

[jsnel]

This works for me.

It will also be fixed eventually in v2.48 but the windows version there's still stuck in rc2, so for now this is the best workaround.