Added ppc64le architecture to support testcases on power machine.

[ashutoshjadhav9]

Some testcases were failing with "unknown architecture ppc64le" error.
Below testcases were failing due to missing ppc64le architecture.

1. Microsoft.AspNetCore.FunctionalTests.dll
2. Microsoft.AspNetCore.Hosting.FunctionalTests.dll
3. ServerComparison.FunctionalTests.dll

So, we have added the power architecture to support those testcases.
Now all the testcases related to power architecture are passing.

[ghost]

Thanks for your PR, @ashutoshjadhav9. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[ashutoshjadhav9]

@dotnet-policy-service agree

@dotnet-policy-service agree

[ghost]

Looks like this PR hasn't been active for some time and the codebase could have been changed in the meantime.
To make sure no breaking changes are introduced, please leave an /azp run comment here to rerun the CI pipeline and confirm success before merging the change.

[halter73]

If we ever have to do this again, we should delete RuntimeArchitecture just start using Architecture directly in our integration tests.

[halter73]

Thanks @ashutoshjadhav9!