Add eos changes for Python3 (#24600)

* eos python3 changes

* changes to convert response from byte to text

* Add dellos6 python3 changes
Make `execute_command` arguments and its
return value complaint to PY3 changes
made in PR #24431

* Fix py3 prompt issue for invalid show command
* Fix review comments
* Add generic fix for error prompt in py3
* Fix CI issue
* Fix network_cli unit test failure

test/sanity/pep8/legacy-files.txt

@@ -43,7 +43,6 @@ lib/ansible/module_utils/connection.py
 lib/ansible/module_utils/database.py
 lib/ansible/module_utils/docker_common.py
 lib/ansible/module_utils/ec2.py
-lib/ansible/module_utils/eos.py
 lib/ansible/module_utils/f5_utils.py
 lib/ansible/module_utils/facts.py
 lib/ansible/module_utils/fortios.py
@@ -808,7 +807,6 @@ lib/ansible/plugins/strategy/debug.py
 lib/ansible/plugins/strategy/free.py
 lib/ansible/plugins/strategy/linear.py
 lib/ansible/plugins/terminal/asa.py
-lib/ansible/plugins/terminal/eos.py
 lib/ansible/plugins/terminal/junos.py
 lib/ansible/plugins/test/core.py
 lib/ansible/plugins/test/files.py

test/units/plugins/connection/test_network_cli.py

@@ -148,7 +148,6 @@ class TestConnectionClass(unittest.TestCase):
         pc = PlayContext()
         new_stdin = StringIO()
         conn = network_cli.Connection(pc, new_stdin)
-
         mock__terminal = MagicMock()
         mock__terminal.terminal_stdout_re = [re.compile(b'device#')]
         mock__terminal.terminal_stderr_re = [re.compile(b'^ERROR')]
@@ -171,9 +170,8 @@ class TestConnectionClass(unittest.TestCase):
         self.assertEqual(output, b'command response')
 
         mock__shell.reset_mock()
-        mock__shell.recv.return_value = b"ERROR: error message"
+        mock__shell.recv.return_value = b"ERROR: error message device#"
 
         with self.assertRaises(AnsibleConnectionFailure) as exc:
             conn.send({'command': b'command'})
-        self.assertEqual(str(exc.exception), 'ERROR: error message')
-
+        self.assertEqual(str(exc.exception), 'ERROR: error message device#')