Revert "Denormalize notes permission data & update when permissions change"

What does this MR do?

Reverts the Elasticsearch migration to denormalize permission data. We found an issue (in staging) with the migration that needs to be fixed before the migration can run on GitLab.com

MR: !52837 (merged)

Backtrace from staging

[ gstg ] production> ElasticIndexBulkCronWorker.new.perform
Traceback (most recent call last):
       16: from lib/gitlab/exclusive_lease_helpers.rb:38:in `in_lock'
       15: from ee/app/workers/concerns/elastic/bulk_cron_worker.rb:22:in `block in perform'
       14: from ee/app/services/elastic/process_bookkeeping_service.rb:83:in `execute'
       13: from ee/app/services/elastic/process_bookkeeping_service.rb:54:in `with_redis'
       12: from lib/gitlab/redis/wrapper.rb:18:in `with'
       11: from lib/gitlab/redis/wrapper.rb:18:in `block in with'
       10: from ee/app/services/elastic/process_bookkeeping_service.rb:83:in `block in execute'
        9: from ee/app/services/elastic/process_bookkeeping_service.rb:105:in `execute_with_redis'
        8: from ee/lib/gitlab/elastic/document_reference.rb:27:in `each'
        7: from ee/lib/gitlab/elastic/document_reference.rb:27:in `each'
        6: from ee/app/services/elastic/process_bookkeeping_service.rb:105:in `block in execute_with_redis'
        5: from ee/app/services/elastic/process_bookkeeping_service.rb:145:in `submit_document'
        4: from ee/lib/gitlab/elastic/bulk_indexer.rb:39:in `process'
        3: from ee/lib/gitlab/elastic/bulk_indexer.rb:65:in `index'
        2: from ee/lib/elastic/multi_version_util.rb:76:in `as_indexed_json'
        1: from ee/lib/elastic/latest/note_instance_proxy.rb:19:in `as_indexed_json'
NoMethodError (undefined method `assignee_ids' for nil:NilClass)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team