[2.7] escape default prompt detection in telnet action plugin (#46573) (#47440)

* [2.7] escape default prompt detection in telnet action plugin (#46573)

This change fixes an issue with the default prompt handling.  The value
needs to be escaped otherwise it does not work when converted to bytes.
(cherry picked from commit 9180d2c)

Co-authored-by: Peter Sprygada <privateip@users.noreply.github.com>

* Add changelog

changelogs/fragments/telent-prompt-fix.yaml

@@ -0,0 +1,4 @@
+---
+bugfixes:
+- Fix an issue with the default telnet prompt handling. The value needs to be
+  escaped otherwise it does not work when converted to bytes.

lib/ansible/plugins/action/telnet.py

@@ -51,7 +51,7 @@ class ActionModule(ActionBase):
 
             login_prompt = self._task.args.get('login_prompt', "login: ")
             password_prompt = self._task.args.get('password_prompt', "Password: ")
-            prompts = self._task.args.get('prompts', ["$ "])
+            prompts = self._task.args.get('prompts', ["\\$ "])
             commands = self._task.args.get('command') or self._task.args.get('commands')
 
             if isinstance(commands, text_type):