[ci]Conditionally turn off multi tasking for arm64 (#21957)

* [ci]Conditionally turn off multi tasking for arm64

* Use var expression in variables instead

* Yet another try

* Fix release CI as well

* Use proper variables on matrix

* Try non-runtime expressions for release CI

* Remove debug prints

.pipelines/ci/templates/build-powertoys-ci.yml

@@ -9,6 +9,7 @@ jobs:
   variables:
     BuildConfiguration: ${{ parameters.configuration }}
     BuildPlatform: ${{ parameters.platform }}
+    useAllCPUsWhileBuildingPowerToys: $[ne(variables['BuildPlatform'],'arm64')] # Multi processor build for arm64 is broken in the latest pipelines update
   pool:
     demands: ImageOverride -equals WinDevVS17-latest
     ${{ if eq(variables['System.CollectionUri'], 'https://dev.azure.com/ms/') }}:

.pipelines/ci/templates/build-powertoys-steps.yml

@@ -71,7 +71,7 @@ steps:
     platform: '$(BuildPlatform)'
     configuration: '$(BuildConfiguration)'
     msbuildArgs: ${{ parameters.additionalBuildArguments }}
-    maximumCpuCount: false # Multi processor build for arm64 is broken in the latest pipelines update
+    maximumCpuCount: '$(useAllCPUsWhileBuildingPowerToys)'
 
 - task: NuGetCommand@2
   displayName: Restore NuGet packages for BugReportTool.sln