remove leftover auto-connect internal endpoint and code

[jschaul]

This is more dead code forgotten to be removed in #1005 when auto-connect was
disabled.

Checklist

• The PR Title explains the impact of the change.
• The PR description provides context as to why the change should occur and what the code contributes to that effect. This could also be a link to a JIRA ticket or a Github issue, if there is one.
• Section Unreleased of CHANGELOG-draft.md contains the following bits of information:
  • A line with the title and number of the PR in one or more suitable sub-sections.

[fisx]

(I'll also bump concourse.)