[release/8.0.1xx] Use new ACR for registry image

[nagilson]

Backport of #49677 to release/8.0.1xx

[nagilson]

@dotnet/sdk-container-builds-maintainers This one will require more code / updating to the oldest logic. Are those changes something we had service approval for in the past / is there a reason they werent ported to 8.0.100?

[nagilson]

Ok, so we need to fix the code here but even if we do that we will still be blocked by #49687

[marcpopMSFT]

@nagilson what are the next steps to getting this unblocked for 8 (looks like 9 and main are green)? The PR appears to need a fix to DockerTestFixture.cs to add .GetAwaiter().GetResult(); For DockerRegistryManager.cs, that one is different enough from main that it's not as straight forward.

[nagilson]

I am not familiar with why the codebase changed so much between 8 and 9. I could investigate that, but @dotnet/sdk-container-builds-maintainers know the code more than I do since they own it, and it would be more efficient for them to look into this. I will defer to them on that unless we want to bump the priority of this.

[marcpopMSFT]

@dotnet/sdk-container-builds-maintainers can ya'll take a look? The containers tests are broken in the 8 branch and this PR needs some help getting it passing with code changes to the containers code.