Add runtime-community.yml pipeline and add s390x job

[akoeplinger]

/cc @steveisok@nealef@uweigand

[ghost]

I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label.

[akoeplinger]

/azp run runtime-community

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[mangod9]

@akoeplinger I am seeing a build break in the outerloop runs on the s390x legs. Was it expected to run as part of outerloop?

https://dev.azure.com/dnceng/public/_build/results?buildId=1417984&view=logs&j=5fb38e2a-2c7b-5c70-04f8-4c22cb90d4ac&t=a0d8571b-3c7b-579b-b288-d6b2fbbcfd35&l=702

[akoeplinger]

@mangod9 no it wasn't, looks like I accidentally copied the in(parameters.platformGroup, 'all', 'gcstress')) }}: which is what I think pulls this into the outerloop run. Will fix it.

[mangod9]

ok, thanks. Assume the build break itself needs a separate investigation or is that known?

[akoeplinger]

CoreCLR wasn't ported to the s390x architecture yet (it's running on Mono), so I'm not surprised it doesn't compile :)

[mangod9]

ah ok, makes sense :)

[directhex]

/backport to release/6.0