Migrate to 1ES hosted pools

[lpatalas]

We are moving to 1ES hosted pools. This PR update pipeline yaml to use new pools.

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

[akoeplinger]

can you please move the linux/mac jobs to ubuntu-latest and macos-latest while you're at it? looks like they're both using the deprecated old pools.

[lpatalas]

I will do that and update the PR.

[lpatalas]

@akoeplinger I updated the pools. The build was failing on macOS-latest but macOS-10.14 works fine.

[akoeplinger]

hmm that's bad since macos-10.14 will be removed soon: https://devblogs.microsoft.com/devops/hosted-pipelines-image-deprecation/

It looks like the repo is still using arcade from the "5.0" branch and was last updated 2 years ago which might be part of the problem.

[akoeplinger]

As far as I know the repo doesn't really ship anymore (the last update of NETStandard.Library on nuget.org is from 2018) so we might not even need CI anymore.

/cc @ericstj @terrajobst

[lpatalas]

Ok, thanks for the info Alex. If we need to do some extra work to upgrade to macos-latest then I would prefer to merge this PR and create separate issue for that.

[akoeplinger]

Yeah I think we can merge this for now and wait for Eric/Immo to reply.