Make mono runtime tests stop using patching

[naricc]

Runtime tests on mono still rely on using the PatchCoreCLRCoreRoot target, for architectures other than Android and Wasm:

runtime/src/mono/mono.proj

Line 105 in ec26ee5

<Target Name="PatchCoreClrCoreRoot">

This step is confusing when running the tests locally, time consuming, and brittle. It was necessary when the tests were first extended to work on mono, but work since should make it possible to use use a corerun build with mono.

Before actually removing the target we also need to make sure that the automated performance runs do not use it. @DrewScoggins

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[naricc]

Also do we need this dependency?

- job: mono_common_test_build_p0_AnyOS_AnyCPU_release
   condition: >-
   and(succeeded(), and(succeeded(), or(
   eq(dependencies.checkout.outputs['SetPathVars_mono.containsChange'], true),
  eq(dependencies.checkout.outputs['SetPathVars_runtimetests.containsChange'], true),
  eq(variables['isFullMatrix'], true))))
 container:
 alias: mcr.microsoft.com/dotnet-buildtools/prereqs:centos-7-359e48e-20200313130914
 continueOnError: false
 dependsOn:
  - checkout
  - coreclr__product_build_Linux_x64_release
  - libraries_build_Linux_x64_Release

[naricc]

I also checked with @DrewScoggins; performance runs are not using that target.

[safern]

@naricc I added blocking-clean-ci as this manifests as:

Artifact CoreCLRProduct__Linux_arm64_release not found for build

Whenever the Mono runtime tests start running before CoreCLR build is done.

[naricc]

@akoeplinger @steveisok I think the easiest way to do this is to use the test host the libraries tests are currently using, instead of corerun (which currently requires building coreclr). Is there any issue if the runtime tests depend on that test host?

[steveisok]

Not that I know of.