Migrate to 1ES hosted pools

[lpatalas]

Moves the pipeline from old Helix based pools to 1ES hosted pools.

Tracking issue: https://github.com/dotnet/core-eng/issues/14276

[lpatalas]

@marcpopMSFT Could we get this merged?

[marcpopMSFT]

@lpatalas I was going to archive this repo once templating repo is switched over to system.commandline. I don't expect any more changes here. I can merge if you think it's needed just in case.

[lpatalas]

@marcpopMSFT The old pools will be retired soon so if we expect to build this repo in the future it would be better to merge this PR just in case. But if you're sure that it won't be built any more then I'm fine with closing this PR. I think I'll leave the decision up to you because you have more context about what's happening with this repo.

[marcpopMSFT]

@baronfel How close is the templating repo move?

[baronfel]

There's a timeout in the PR blocking full merge, but I think it's transient. We hope to merge imminently. PR in question is dotnet/templating#4222