Check controlpersist (#17443)

* Add a new config option to cache the check for controlpersist on the
control machine.

Fixes #15844

* Remove the option and make the behavior the default

* Make the check for controlpersist cache its status per-ssh executable

lib/ansible/inventory/__init__.py

@@ -21,6 +21,7 @@ __metaclass__ = type
 
 import fnmatch
 import os
+import subprocess
 import sys
 import re
 import itertools