Work items indexing notes causing db timeouts

Summary

Two MRs recently introduced notes fields and backfilled them in the work items index.

• Start populating notes and notes_internal indexes (!170290 - merged)
• Add migration to reindex all work items to capt... (!174463 - merged)

We're seeing db timeouts and failures in the indexing pipeline. kibana (internal)

Steps to reproduce

TBD

What is the current bug behavior?

Indexing fails due to timeout grabbing notes for a work item

What is the expected correct behavior?

Indexing should not fail

Relevant logs and/or screenshots

Possible fixes

The populate_notes method in Search::Elastic::References::WorkItem probably needs to be modified to use batching, but we need to do testing to see what batch size works