Ensure highlight.max_analyzed_offset matches the max size of documents being indexed to avoid search 500

The following discussion from !33176 (merged) should be addressed:

• @mbergeron started a discussion: (+1 comment)

  @dgruzd one thing that comes to mind is why the gitlab-elasticsearch-indexer has a different configuration value at all — should the sidekiq worker push down its own config to make sure we don't have a split in the future?