Make sure the final WiX bundle contains a *signed* MSI (#17446)

* Make sure the *signed* MSI makes it into the bundle

* And don't let Bootstrapper force-build MSI

* Revert "And don't let Bootstrapper force-build MSI"

This reverts commit 77cea11008.

* try this wacky hacky sacky thing

* Revert "Revert "And don't let Bootstrapper force-build MSI""

This reverts commit 7d25009932.

* Revert "try this wacky hacky sacky thing"

This reverts commit 0fea6df635.

* ah the things i hate

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

@@ -92,13 +92,24 @@ steps:
     restoreDirectory: '$(Build.SourcesDirectory)\installer\packages'
 
 - task: VSBuild@1
-  displayName: 'Build PowerToysSetup.sln'
+  displayName: 'Build PowerToys MSI'
   inputs:
     solution: '**\installer\PowerToysSetup.sln'
     vsVersion: 17.0
     platform: '$(BuildPlatform)'
     configuration: '$(BuildConfiguration)'
-    msbuildArgs: ${{ parameters.additionalBuildArguments }}
+    msbuildArgs: /t:PowerToysInstaller ${{ parameters.additionalBuildArguments }}
+    maximumCpuCount: true
+
+- task: VSBuild@1
+  displayName: 'Build PowerToys Bootstrapper'
+  inputs:
+    solution: '**\installer\PowerToysSetup.sln'
+    vsVersion: 17.0
+    platform: '$(BuildPlatform)'
+    configuration: '$(BuildConfiguration)'
+    msbuildArgs: /t:PowerToysBootstrapper ${{ parameters.additionalBuildArguments }}
+    clean: false
     maximumCpuCount: true
 
 # directly not doing WinAppDriver testing