Fix process invocation for PowerShell handler (#1080)

* Replaced the method of process awaiting

Author: DenisNikulin5

powershell/VstsTaskSdk/ToolFunctions.ps1

@@ -202,13 +202,9 @@ function Invoke-Process {
             $processOptions.Add("RedirectStandardError", $StdErrPath)
         }
 
-        # TODO: For some reason, -Wait is not working on agent.
-        # Agent starts executing the System usage metrics and hangs the step forever.
+        # We can't use -Wait in this case as it waits for the whole process tree, it can lead to unexprected hangs
         $proc = Start-Process @processOptions
-
-        # https://stackoverflow.com/a/23797762
-        $null = $($proc.Handle)
-        $proc.WaitForExit()
+        Wait-Process -InputObject $proc
 
         $procExitCode = $proc.ExitCode
         Write-Verbose "Exit code: $procExitCode"

powershell/package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "vsts-task-sdk",
-  "version": "0.21.1",
+  "version": "0.21.2",
   "private": true,
   "scripts": {
     "build": "node make.js build",
@@ -16,6 +16,6 @@
     "mocha": "5.2.0",
     "nodejs-file-downloader": "^4.11.1",
     "shelljs": "^0.8.5",
-    "typescript": "^4.0.2"
+    "typescript": "4.0.2"
   }
 }