Remove workaround for microbuild plugin bug

The bug is now fixed.

init.ps1

@@ -129,11 +129,6 @@ try {
         $EnvVars['LocLanguages'] = "JPN"
     }
 
-    # This is a workaround for https://dev.azure.com/devdiv/DevDiv/_workitems/edit/1283978
-    if ($Signing -or $Setup -or $OptProf -or $Localization) {
-        & $InstallNuGetPkgScriptPath MicroBuild.Core.Sentinel -source $MicroBuildPackageSource -Verbosity $nugetVerbosity
-    }
-
     & "$PSScriptRoot/tools/Set-EnvVars.ps1" -Variables $EnvVars | Out-Null
 }
 catch {