Fix order-dependent Elasticsearch spec failure

What does this MR do and why?

This backports !159814 (merged) to 17-1-stable-ee.

ee/spec/workers/search/elastic/trigger_indexing_worker_spec.rb appears to be creating Elasticsearch indexes and not cleaning up. This appears to cause ee/spec/models/concerns/search/elastic/issues_search_spec.rb to fail.

Relates to gitlab-org/release/tasks#11763 (closed)

MR acceptance checklist

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How to set up and validate locally

Run:

bundle exec rspec ee/spec/workers/search/elastic/trigger_indexing_worker_spec.rb ee/spec/models/concerns/search/elastic/issues_search_spec.rb