[ArPow] Remove runtime patch

[dseefeld]

As part of dotnet/installer#11506 a patch was introduced to build allconfigurations only when building non-portable. This issue is addressed in dotnet/runtime#58122. Once this change is picked up by source-build, the patch can be removed.

[MichaelSimons]

Another patch was added as part of #2404 which should also get backported.