[Heartbeat] Autodiscover monitor config collisions

[justinkambic]

In an attempt to create a fix for the issue described in https://github.com/elastic/sdh-beats/issues/1402 we think we may have found an issue whereby Heartbeat's usage of autodiscover creates multiple configs with the same hash.

Of particular interest is this code, which seems to store the event ID and hash rather than the config hash itself. We are wondering if it makes more sense to attempt to avoid multiple instances of the same config.

There is a community PR for tangential changes; it mentions modifying the way autodiscover works to dedupe config usage.

[elasticmachine]

Pinging @elastic/uptime (Team:Uptime)

[justinkambic]

Fixed by #29048.