hosts/windows: use subprocess to execute mstsc [GH-3837]

CHANGELOG.md

@@ -26,6 +26,8 @@ BUG FIXES:
       not accessing the local host. [GH-3861]
   - guests/windows: Fix errors with arg lists that are too long over
       WinRM in some cases. [GH-3816]
+  - hosts/windows: Don't execute mstsc using PowerShell since it doesn't
+      exit properly. [GH-3837]
   - providers/docker: Never do graceful shutdown, always use
       `docker stop`. [GH-3798]
   - providers/docker: Better error messaging when SSH is not ready

plugins/hosts/windows/cap/rdp.rb

@@ -1,6 +1,6 @@
 require "tempfile"
 
-require "vagrant/util/powershell"
+require "vagrant/util/subprocess"
 
 module VagrantPlugins
   module HostWindows
@@ -29,7 +29,7 @@ module VagrantPlugins
           end
 
           # Launch it
-          Vagrant::Util::PowerShell.execute("mstsc", *args)
+          Vagrant::Util::Subprocess.execute("mstsc", *args)
         ensure
           config.close if config
         end