SSH Public Key missing from Repository Mirror created through API
### Summary
Repository Mirror (push) created through GitLab API via `curl` commands does not include SSH Public Key which can be copied for pasting into remote `authorized_keys` file.
### Steps to reproduce
1. Set GitLab access token as environment variable:
`export GITLAB_TOKEN=xxxxxxxxxxxxxxx`
2. POST request to create repository mirror using SSH authentication, e.g.:
```
curl --request POST \
--data "url=ssh://josh@rhel6-64.slac.stanford.edu/sdf/group/supercdms/backups/git-backup/CompInfrastructure/cdms-jupyterlab.git" \
--data "enabled=yes" \
--data "keep_divergent_refs=yes" \
--header "PRIVATE-TOKEN: $GITLAB_TOKEN" "https://gitlab.com/api/v4/projects/12571860/remote_mirrors"
```
### Example Project
Example project: CDMS JupyterLab - https://gitlab.com/supercdms/CompInfrastructure/cdms-jupyterlab
### What is the current *bug* behavior?
Under project settings -> repository -> mirroring repositories, "Remove" and "Update Now" buttons are visible, but no "Copy SSH public key" button.
### What is the expected *correct* behavior?
"Copy SSH public key" button for mirror created both via curl command and web UI.
### Relevant logs and/or screenshots

### Output of checks
This bug happens on GitLab.com
### Possible fixes
My first thought was that perhaps the POST command is expecting an http url by default.
I looked through the [API]((https://docs.gitlab.com/ee/api/remote_mirrors.html#create-a-remote-mirror
) for remote mirrors to find a field to specify type of url (ssh vs. http) but nothing is specified.
issue