Update mimalloc to v2.2.4 (after Git for Windows v2.50.0 is released)

[dscho]

Upgrade Git for Windows by vendoring in mimalloc v2.2.4 which was released yesterday.

Seeing as the update to v2.2.3 brought a bug that was only revealed after Git for Windows v2.50.0-rc0 made it into Git for Windows' SDK, I do not want to update to v2.2.4 just yet, especially given that the diff between v2.2.3 and v2.2.4 brings more functional changes than just the fix for aforementioned bug.

After Git for Windows v2.50.0 is released (plus a grace period of 1-2 weeks or so in case of a hot-fix release), I would like to upgrade to mimalloc v2.2.4, and while at it, also start monitoring https://github.com/microsoft/mimalloc/tags in the component-updates.yml workflow.

[rimrul]

Ok, we might need to add a different form or revert 0f09e10, this looked painfull

[dscho]

Ok, we might need to add a different form or revert 0f09e10, this looked painfull

@rimrul it wasn't actually too bad, I just filled in throw-away text into the mandatory parts of the form, and then edited the free-form text.

Besides, I would not want to make it too easy for random drive-by "contributors" to add work items "for someone else to take care of". The inclination to do such things seems to be very strong in some people, and it is a constant source of frustration that open source has less than no need of.

tl;dr I think we can keep the form and don't need to add another one.