Expose the ssh diagnostic message
Expose the ssh diagnostic message

When git-sync fails to clone the git project, the ssh diagnostic message
is suppressed. It is sometimes helpful for debugging the cloning issue.
One example of the ssh dianostic message is
```
ssh: Could not resolve hostname ${REPO_HOST}: Name or service not known
```

This commit removes the `-q` flag from the ssh command to expose such
message.

kubernetes/git-sync,kubernetes/git-sync