Add until_executed deduplication strategy

What does this MR do?

While working on POC - Image Resizing: Resizing via Sidekiq, we needed to introduce new :until_executed deduplication strategy which locks until the previously scheduled job finishes (gitlab-com/gl-infra/scalability#195).

This MR introduces until_executed deduplication strategy - It locks until the previously scheduled job finishes. It should prevent background jobs to be running simultaneously multiple times.

Related to #241378 (closed)

Conformity

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