Override LFK cleanup worker feature category for error routing

What does this MR do and why?

Currently when the LFK cleanup worker generates failures, every alert goes to the database frameworks team even for tables that don't belong to the database frameworks team. The solution is to override the feature category during the LFK cleanup stage to correctly identify the responsible team based on table ownership, ensuring alerts are routed to the appropriate channels.

Note to the Reviewers:

I took the current tests and moved them to a shared context. The goal is to make sure the current tests all pass when the feature flag is both enabled and disabled. So the structure is:

• setup tests/create table structure (currently on master)
• #child_table_feature_category (my additions)
• #feature_category_override_enabled? (my additions)
• shared examples (currently on master)
• Feature flag enabled (my addition)
• Feature flag disabled
(my addition)

References

#573367

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