Register via TTL check for nodes with no agents

[andrewstucki]

Changes proposed in this PR:

This swaps the health check that's registered as part of the exec process to use TTL-based checks in Consul.

Checklist:

• Tests added
• CHANGELOG entry added

  Run make changelog-entry for guidance in authoring a changelog entry, and
  commit the resulting file, which should have a name matching your PR number.
  Entries should use imperative present tense (e.g. Add support for...)

[mikemorris]

Is there any significant downside to having this always enabled, even when running with Consul servers in the same network or Kubernetes cluster?

[nathancoleman]

Andrew Stucki
13 hours ago
Sorry, just saw this -- actually chatted with Mike about that offline awhile ago, there's no downside