(Subtask to achieve SERVER-84243 - Dedicate a catalog cache and loader to the shard role. For more information refer to this document)

 
SERVER-95393 introduced a dedicated catalog cache loader (SSCCL) and catalog cache for the shard role, as well as another loader (CSCCL) and catalog cache for the router role. These changes are currently protected by a fully disabled feature flag, gCatalogCacheSplit.

As a result, unit tests do not cover these changes since there is no build variant that enforces the feature flag to be set to true while running the unit tests.

The goal of this ticket is to create unit tests that dedicate a loader and catalog cache to each role, similar to how the production code is structured with the protection of the feature flag. To test this work stream, we will need to enable the feature flag; however, implementing a suite/build variant to do this is not part of the current ticket.