[Elasticsearch] Camel cased words should be split into smaller tokens

https://gitlab.zendesk.com/agent/tickets/69197

If you have method like def requeuePendingConversion you should be able to find it by requeuePending It used to work, so it seems like a regression. I fixed it and we even have a spec for this https://gitlab.com/gitlab-org/gitlab-elasticsearch-git/blob/master/spec/main_spec.rb#L55

Should be investigated because it makes ES search not really useful.

I reproduced it for master