icingadb: use object identifiers for state history event IDs

[00Manas-Singh00]

State history IDs in the Icinga DB publisher were derived from object names, which can collide in HA setups where similarly named checks exist on different masters. This could cause service history entries to appear mixed between hosts/endpoints.

This change makes state history identity use the stable Icinga DB object identifier instead of raw object name:

CalcEventID(...) now hashes GetObjectIdentifier(object) (not object->GetName()).
SendStateChange(...) now builds history id from {environment_id, object_identifier, event_ts}.

[julianbrost]

State history IDs in the Icinga DB publisher were derived from object names, which can collide in HA setups where similarly named checks exist on different masters.

The object name is what identifies the object in Icinga 2. If it has the same name, it's the same thing. Service::GetName() will return something like mail.example.com!ping, so there shouldn't be a conflict between identically named services belonging to different hosts either.

Then there are also these general issues with this PR:

• It looks like this PR also includes commits from your older PR. Please remove them here so that this only contains the relevant changes.
• Also, this sounds like it's related to Service history of checks, applied directly to masters, is mixed up between each other #10835 (comment), so please cross-reference the issue by adding fixes #10835 to the description here.