Fix broken master: Use clean_gitlab_redis_cache for test

What does this MR do?

This MR fixes a master:broken #337390 (closed).

The test group was previously using :clean_gitlab_redis_shared_state, whereas the caching class Gitlab::Cache::Import::Caching caches with Gitlab::Redis::Cache.

Does this MR meet the acceptance criteria?

Conformity

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• I have self-reviewed this MR per code review guidelines.
• This MR does not harm performance, or I have asked a reviewer to help assess the performance impact. (Merge request performance guidelines)
• I have followed the style guides.
• This change is backwards compatible across updates, or this does not apply.

Availability and Testing

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Security

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• 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