Update Debian11 Arm64 queue to Debian12

[wtgodbe]

We'll keep the Amd64 image on Debian11 until msquic is available (#46418)

[dougbu]

Do we have an issue tracking our inability to test templates in the ARM Debian 11 / 12 image❔

[wtgodbe]

Looks like we started skipping them as of #41563 because they were taking too long - @DamianEdwards do you have any more info there (did we open an issue for that?). I can try running the tests on that queue to see if the issue has been fixed

[wtgodbe]

arm64 template tests are running now in #46273

[DamianEdwards]

I think this was the issue tracking template tests on ARM? #28090

[dougbu]

I don't remember exactly what the testing I mentioned in #28090 showed. But it's unfortunate I didn't change anything (that I can remember) about testing the templates in branches other than release/6.0.

Note we'll need to run #46273 a few times to make sure the templates tests are fine on Debian 12. May be worth testing on Debian 11 as well since we need to keep the 11 / 12 platform split. (.NET 8 will definitely support Debian 11 still.)

[wtgodbe]

I've unskipped the project template tests on debian arm, got sufficient confirmation from #46273 that the slowdown is minimal