Remove Ruby elasticsearch repository indexer

See the port to CE here: gitlab-foss!32629 (closed)

What does this MR do?

Remove Ruby elasticsearch repository indexer

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.

Related to #6481 (closed)