[ci] Remove some Classic XA test stages/jobs. (#7770)

Super easy win to kick off removing Classic from `main`:

Remove the `Legacy Tests` stage and `MSBuild+Emulator Legacy #X` jobs.

These definitely are already running .NET equivalents, and will reduce
our CI per-run cost by ~11.5 CPU hours (out of ~39.5 hours total).

Author: jpobst

build-tools/automation/azure-pipelines.yaml

@@ -562,82 +562,6 @@ stages:
 
     - template: yaml-templates/fail-on-issue.yaml
 
-- stage: msbuild_legacy
-  displayName: Legacy Tests
-  dependsOn: mac_build
-  # Disabled on .NET release branches
-  condition: and(succeeded(), eq(variables.IsRelOrTargetingRel, 'False'), or(eq(variables['RunAllTests'], true), contains(dependencies.mac_build.outputs['mac_build_create_installers.TestConditions.TestAreas'], 'MSBuild')))
-  jobs:
-  # Xamarin.Android (Test MSBuild Legacy - macOS)
-  - template: yaml-templates\run-msbuild-mac-tests.yaml
-    parameters:
-      node_id: 1
-      job_name: mac_msbuild_tests_1
-      job_suffix: Legacy
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  - template: yaml-templates\run-msbuild-mac-tests.yaml
-    parameters:
-      node_id: 2
-      job_name: mac_msbuild_tests_2
-      job_suffix: Legacy
-      run_extra_tests: true
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  - template: yaml-templates\run-msbuild-mac-tests.yaml
-    parameters:
-      node_id: 3
-      job_name: mac_msbuild_tests_3
-      job_suffix: Legacy
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  - template: yaml-templates\run-msbuild-mac-tests.yaml
-    parameters:
-      node_id: 4
-      job_name: mac_msbuild_tests_4
-      job_suffix: Legacy
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  - template: yaml-templates\run-msbuild-mac-tests.yaml
-    parameters:
-      node_id: 5
-      job_name: mac_msbuild_tests_5
-      job_suffix: Legacy
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  - template: yaml-templates\run-msbuild-mac-tests.yaml
-    parameters:
-      node_id: 6
-      job_name: mac_msbuild_tests_6
-      job_suffix: Legacy
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  # Xamarin.Android (Test MSBuild Legacy - Windows)
-  - template: yaml-templates\run-msbuild-win-tests.yaml
-    parameters:
-      node_id: 1
-      additional_node_id: 4
-      job_name: win_msbuild_tests_1
-      job_suffix: Legacy
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  - template: yaml-templates\run-msbuild-win-tests.yaml
-    parameters:
-      node_id: 2
-      additional_node_id: 5
-      job_name: win_msbuild_tests_2
-      job_suffix: Legacy
-      run_extra_tests: true
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
-  - template: yaml-templates\run-msbuild-win-tests.yaml
-    parameters:
-      node_id: 3
-      additional_node_id: 6
-      job_name: win_msbuild_tests_3
-      job_suffix: Legacy
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-
 - stage: msbuild_dotnet
   displayName: One .NET Tests
   dependsOn: mac_build
@@ -734,44 +658,6 @@ stages:
   dependsOn: mac_build
   condition: and(succeeded(), or(eq(variables['RunAllTests'], true), contains(dependencies.mac_build.outputs['mac_build_create_installers.TestConditions.TestAreas'], 'MSBuildDevice')))
   jobs:
-  # Check - "Xamarin.Android (macOS > Tests > MSBuild+Emulator Legacy #N)"
-  - template: yaml-templates/run-msbuild-device-tests.yaml
-    parameters:
-      node_id: 1
-      job_name: mac_msbuilddevice_tests_1
-      job_suffix: Legacy
-      nunit_categories: '&& cat != Debugger'
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-      jobCondition: and(succeeded(), eq(variables.IsRelOrTargetingRel, 'False'))
-
-  - template: yaml-templates/run-msbuild-device-tests.yaml
-    parameters:
-      node_id: 2
-      job_name: mac_msbuilddevice_tests_2
-      job_suffix: Legacy
-      nunit_categories: '&& cat != Debugger'
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-      jobCondition: and(succeeded(), eq(variables.IsRelOrTargetingRel, 'False'))
-
-  - template: yaml-templates/run-msbuild-device-tests.yaml
-    parameters:
-      node_id: 3
-      job_name: mac_msbuilddevice_tests_3
-      job_suffix: Legacy
-      nunit_categories: '&& cat != Debugger'
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-      jobCondition: and(succeeded(), eq(variables.IsRelOrTargetingRel, 'False'))
-
-  - template: yaml-templates/run-msbuild-device-tests.yaml
-    parameters:
-      node_id: 4
-      job_name: mac_msbuilddevice_tests_with_debugger
-      job_suffix: Legacy
-      jdkTestFolder: $(XA.Jdk11.Folder)
-      nunit_categories: '&& cat == Debugger'
-      provisionatorChannel: ${{ parameters.provisionatorChannel }}
-      jobCondition: and(succeeded(), eq(variables.IsRelOrTargetingRel, 'False'))
-
   # Check - "Xamarin.Android (macOS > Tests > MSBuild+Emulator One .NET #N)"
   - template: yaml-templates/run-msbuild-device-tests.yaml
     parameters: