[config reload] Call systemctl reset-failed for snmp,telemetry,mgmt-framework services (sonic-net#1773)

#### What I did

When issue `config reload -y` or `config load_minigraph -y` command, most of the sonic services will be reset by command `systemctl reset-failed <service_name>`. The purpose is to avoid services reach to its start retry limit and cannot be started. However, `systemctl reset-failed` only resets those services belong to sonic.target, snmp, telemetry and mgmt-framework are not part of them. So if we run `config reload -y` or `config load_minigraph -y` continues, snmp, telemetry and mgmt-framework services might enter into failed state. This PR is to fix the issue.

I would like to cherry-pick this fix to 202012 branch, but this fix also depends on PR sonic-net#7846. So if we decide to cherry-pick this PR to 202012, we need cherry-pick sonic-net#7846 first.

#### How I did it

Also call `systemctl reset-failed` for services like snmp, telemetry and mgmt-framework. 

#### How to verify it

Manual test.

Author: Junchao-Mellanox

config/main.py

@@ -691,11 +691,16 @@ def _stop_services():
 
 def _get_sonic_services():
     out = clicommon.run_command("systemctl list-dependencies --plain sonic.target | sed '1d'", return_cmd=True)
-    return [unit.strip() for unit in out.splitlines()]
+    return (unit.strip() for unit in out.splitlines())
+
+
+def _get_delayed_sonic_services():
+    out = clicommon.run_command("systemctl list-dependencies --plain sonic-delayed.target | sed '1d'", return_cmd=True)
+    return (unit.strip().rstrip('.timer') for unit in out.splitlines())
 
 
 def _reset_failed_services():
-    for service in _get_sonic_services():
+    for service in itertools.chain(_get_sonic_services(), _get_delayed_sonic_services()):
         clicommon.run_command("systemctl reset-failed {}".format(service))
 
 

tests/config_test.py

@@ -35,7 +35,13 @@ def mock_run_command_side_effect(*args, **kwargs):
         click.echo(click.style("Running command: ", fg='cyan') + click.style(command, fg='green'))
 
     if kwargs.get('return_cmd'):
-        return ''
+        if command == "systemctl list-dependencies --plain sonic-delayed.target | sed '1d'":
+            return 'snmp.timer'
+        elif command == "systemctl list-dependencies --plain sonic.target | sed '1d'":
+            return 'swss'
+        else:
+            return ''
+
 
 class TestLoadMinigraph(object):
     @classmethod
@@ -55,7 +61,11 @@ def test_load_minigraph(self, get_cmd_module, setup_single_broadcom_asic):
             traceback.print_tb(result.exc_info[2])
             assert result.exit_code == 0
             assert "\n".join([l.rstrip() for l in result.output.split('\n')]) == load_minigraph_command_output
-            assert mock_run_command.call_count == 7
+            # Verify "systemctl reset-failed" is called for services under sonic.target 
+            mock_run_command.assert_any_call('systemctl reset-failed swss')
+            # Verify "systemctl reset-failed" is called for services under sonic-delayed.target 
+            mock_run_command.assert_any_call('systemctl reset-failed snmp')
+            assert mock_run_command.call_count == 10
 
     def test_load_minigraph_with_port_config_bad_format(self, get_cmd_module, setup_single_broadcom_asic):
         with mock.patch(