Make interprocess polling interval configurable (#16560)

As recently there was back-and-forth with this hardcoded value
(0.001 -> 0.01 -> 0.005), obviousely the optimal value for it depends on
Ansible usage scanario and is better to be configurable.

This patch adds a new config option in DEFAULT section,
`internal_poll_interval`, with default of 0.001 corresponding to the
value hardcoded in Ansible v2.1.
This config option is then used instead of hardcoded values where
needed.

Related GH issue: 14219

lib/ansible/plugins/strategy/__init__.py

@@ -26,6 +26,7 @@ from collections import deque
 from multiprocessing import Lock
 from jinja2.exceptions import UndefinedError
 
+from ansible import constants as C
 from ansible.compat.six.moves import queue as Queue
 from ansible.compat.six import iteritems, string_types
 from ansible.errors import AnsibleError, AnsibleParserError, AnsibleUndefinedVariable
@@ -530,7 +531,7 @@ class StrategyBase:
             results = self._process_pending_results(iterator)
             ret_results.extend(results)
             if self._pending_results > 0:
-                time.sleep(0.001)
+                time.sleep(C.DEFAULT_INTERNAL_POLL_INTERVAL)
 
         display.debug("no more pending results, returning what we have")