Scope installer tests to installer changes, keep osx_arm64 for coreclr

Change Installer_Build_And_Test job conditions from
non_mono_and_wasm.containsChange to installer.containsChange for most
platforms. Previously, installer helix tests (5 platforms) ran on any
non-mono change including pure coreclr or libraries changes.

Split osx_arm64 into its own block with a broader condition that also
includes coreclr.containsChange, per Elinor Fung's guidance that Mac
ARM64 is most likely to catch single-file issues from coreclr changes.

- windows_x86, osx_x64: installer OR rolling only
- windows_x64, linux_x64: installer OR rolling only
- osx_arm64: coreclr OR installer OR rolling

Saves 4 helix jobs on coreclr-only PRs (was 5, now 1 remains).
Saves 5 helix jobs on libraries-only PRs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: davidwrighton

eng/pipelines/runtime.yml

@@ -1495,7 +1495,7 @@ extends:
                   creator: dotnet-bot
             condition:
               or(
-                eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_non_mono_and_wasm.containsChange'], true),
+                eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_installer.containsChange'], true),
                 eq(variables['isRollingBuild'], true))
 
       - template: /eng/pipelines/common/platform-matrix.yml
@@ -1504,7 +1504,6 @@ extends:
           buildConfig: release
           platforms:
             - windows_x64
-            - osx_arm64
             - linux_x64
           helixQueuesTemplate: /eng/pipelines/installer/helix-queues-setup.yml
           jobParameters:
@@ -1527,7 +1526,39 @@ extends:
                   creator: dotnet-bot
             condition:
               or(
-                eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_non_mono_and_wasm.containsChange'], true),
+                eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_installer.containsChange'], true),
+                eq(variables['isRollingBuild'], true))
+
+      # osx_arm64 installer tests also run on coreclr changes to catch single-file issues
+      - template: /eng/pipelines/common/platform-matrix.yml
+        parameters:
+          jobTemplate: /eng/pipelines/common/global-build-job.yml
+          buildConfig: release
+          platforms:
+            - osx_arm64
+          helixQueuesTemplate: /eng/pipelines/installer/helix-queues-setup.yml
+          jobParameters:
+            nameSuffix: Installer_Build_And_Test
+            buildArgs: -s host+packs -c $(_BuildConfig) -lc ${{ variables.debugOnPrReleaseOnRolling }} -rc Release
+            dependsOnGlobalBuilds:
+              - nameSuffix: CoreCLR_Libraries
+                buildConfig: ${{ variables.debugOnPrReleaseOnRolling }}
+            preBuildSteps:
+              - template: /eng/pipelines/common/download-artifact-step.yml
+                parameters:
+                  artifactName: CoreCLR_Libraries_BuildArtifacts_$(osGroup)$(osSubgroup)_$(archType)_$(debugOnPrReleaseOnRolling)
+                  artifactFileName: CoreCLR_Libraries_BuildArtifacts_$(osGroup)$(osSubgroup)_$(archType)_$(debugOnPrReleaseOnRolling)$(archiveExtension)
+                  unpackFolder: $(Build.SourcesDirectory)/artifacts/bin
+                  displayName: 'unified artifacts'
+            timeoutInMinutes: 150
+            postBuildSteps:
+              - template: /eng/pipelines/installer/helix.yml
+                parameters:
+                  creator: dotnet-bot
+            condition:
+              or(
+                eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_coreclr.containsChange'], true),
+                eq(stageDependencies.EvaluatePaths.evaluate_paths.outputs['SetPathVars_installer.containsChange'], true),
                 eq(variables['isRollingBuild'], true))
 
       #