Clear Redis-queues on Sidekiq::Testing.inline!

What does this MR do?

Since in specs we run though all the middleware for Sidekiq jobs, and that Sidekiq middleware writes to Redis for job deduplication we should clear that Redis before and after each spec to make sure that the idempotency keys don't bleed into other specs.

The client middleware for job-deduplication writes a key to redis. The server middleware removes it again before running the job. If the spec were to get interrupted between these 2 steps, then the key could remain in Redis causing failures on the next run in development.

Fixes #216732 (closed)

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