insights: retry queries that encounter `shard-timeout` events

Created by: leonore

closes #36226 (closed)

also adds logging for skipped reasons in the JIT path as we didn't have it there

Test plan

Artificially added a shard timeout event in search's progress handler (couldn’t figure out how to hit it locally).

	skipped := []Skipped{
		{
			Reason:  ShardTimeout,
			Title:   "shard-timeout-leo",
			Message: "i'm fake!",
		},
	}

Observed it from search:

Observed it from JIT insight:

And then created a backend insight, saw the error in the insights_query_runner_job queue, which eventually succeeded after retrying once the artificial event was removed and the retry period had passed.

Once this is landed there will be a post-merge test on k8s.sgdev to see if backfill works better