Log heartbeats during the first daemon iteration (while keeping the first error heartbeat)
Summary: I realized that to get the full benefits of https://dagster.phacility.com/D6641 (avoiding the situation where a bunch of schedules/sensors cause an iteration to take more than 2 minutes and trigger a heartbeat failure), we need to be heartbeating more often on the first iteration as well. To still accomplish the goal of not incorrectly saying that the daemon is healthy, I added logic to ensure we log a heartbeat with an error the first time one comes up. This could lead us to incorrectly saying the first iteration is healthy, but I think that's better than the daemon crashing due to a long first iteration.
Test Plan: Integration, BK (see channes to error test)
Reviewers: johann, prha
Reviewed By: johann
Differential Revision: https://dagster.phacility.com/D6654