Remove expirmental marker for git-switch(1) and git-restore(1)

In 4e43b7ff (Declare both git-switch and git-restore experimental, 2019-04-25), the newly introduced git-switch(1) and git-restore(1) commands were marked as experimental. This was done to provide time to make breaking changes to the interface and originally intended for for a couple of releases.

The git-switch(1) and git-restore(1) commands have been marked as experimental for over five years without any significant changes or updates to their functionality. During this time, there has been no ongoing discussion regarding potential breaking changes that would necessitate the experimental label.

By removing the experimental marker, we help clarify the stability and maturity of these commands. This change will make it easier for users to adopt and recommend these commands, as the experimental label has been a point of hesitation for many. Given the lack of changes and continued stability, it's now appropriate to mark these commands as fully supported.

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Digging through past mailing list discussions Last attempt on the mailing list: https://lore.kernel.org/git/20240220092957.1296283-2-matttbe@kernel.org/

This was almost a year ago and it looks like there wasn't much push back. There also haven't been any git-switch(1) and git-restore(1) changes.