[BUG] ping message isn't filtered by Channel Id (mattermost)

[daegeun-ha]

Describe the bug
ping message isn't filtered by channel id.

To Reproduce
Steps to reproduce the behavior:

1. Make two different channels in same mattermost team.
2. Figure one channel to botkube pod. (botkube pod only knows one channel)
3. Send 'ping' message from two different channels.
4. You can see 'pong' message in both channels!

Expected behavior
Only one figured pod that is figured in botkube pod can receive 'pong' message

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context

[PrasadG193]

@daegeun-ha By design ping and kubectl commands are expected to run anywhere. To execute kubectl commands outside of configured channel, you have to pass --cluster-name flag. ping command can run without --cluster-name flag. Please execute /botkubehelp if you have configured Slash command in Mattermost
https://www.botkube.io/installation/mattermost/#h-install-BotKube-slashcommand
Please see: https://www.botkube.io/usage/#h-specify-cluster-name

[daegeun-ha]

I checked it. Thanks :)