Enables multiple_cache_per_job feature flag by default

What does this MR do?

Enables the multiple_cache_per_job feature flag by default. This is the penultimate step in the rollout of the flag. The code will be removed in two weeks after monitoring that it's safe to do so.

Rollout issue:#321877 (closed)
Feature issue: #32814 (closed)

Does this MR meet the acceptance criteria?

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