Add possibility to configure sshd_config in gitlab-shell via the Helm chart

Summary

Our deployment system has multiple (~30) workers and they run simultaneously trying to get the config from Gitlab repository. But some of them get this response from Gitlab:

ssh_exchange_identification: Connection closed by remote host
fatal: Could not read from remote repository.
Please make sure you have the correct access rights, and the repository exists.

Seems that MaxStartups key in the sshd_config can help: https://gitlab.com/gitlab-org/gitlab-ce/issues/24360

Could you please provide the possibility to configure it via the Helm chart?

I can send a MR if you're interested in it.

Steps to reproduce

See above.

Configuration used

See above.

Current behavior

See above.

Expected behavior

See above.

Versions

• Chart: c8a4bf82
• Platform:
  • Self-hosted: Kubernetes
• Kubernetes: (kubectl version)
  • Client: 1.9.3
  • Server: 1.9.3
• Helm: (helm version)
  • Client: 2.8.2
  • Server: 2.8.2

Relevant logs

None