This ticket is for the comprehensive refactoring of the codebase to replace all instances of legacy terminology with the new, approved naming convention from WRITING-29494.

This is a big effort to update references within the code itself, including class names, variable names, function names, comments, and log messages. This change will improve clarity and make the code easier to navigate and understand.

Scope:

• Replace Local Catalog or Shard-Local Catalog with Shard Catalog.

• Replace Cluster Catalog or Sharding Catalog with Global Catalog.

• Replace Cluster DDL with Global DDL.

• Replace Catalog Cache with Routing Cache.

• Update any other internal references to align with the module names: Shard Role, Router Role, and Topology.

Note: This is a large task and could be broken down into sub-tasks, one for each major module rename.