[Synthetics] Paginating sync requests

[lucasfcosta]

Summary

Kibana currently syncs all monitors in a single request. That could cause problems if users have way too many monitors, making Kibana exceed the maximum allowed payload size.

We should make sure that Kibana will paginate these sync requests when necessary to avoid reaching that large payload size.

[elasticmachine]

Pinging @elastic/uptime (Team:uptime)

[dominiqueclarke]

We already pagination sync requests in groups of 500. We may consider reducing the size of the group to around 100.

Thoughts @andrewvc ?

[andrewvc]

@dominiqueclarke it sounds like @lucasfcosta was mistaken when this issue was made then, is that correct?

If so, I do think that 500 sounds a bit large, I'm just worried about excessive memory usage for larger collections of journeys. Ideally we'd do some tests around memory usage, but we don't have time for that. I'd say lowering it to 100 is probably a good balance of memory and efficiency since this is a background process we're talking about.

[dominiqueclarke]

Resolved by #148634