Summary:
An internal user wants to implement a key-aware row cache policy. For that, they need to know the components of the cache key, especially the user key component. With a specialized `RowCache` interface, we will be able to tell them the components so they won't have to make assumptions about our internal key schema.
This PR prepares for the specialized `RowCache` interface by updating the migration plan of https://github.com/facebook/rocksdb/issues/11450. I added a release note for the removed APIs and didn't mention the added ones for now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/11620
Reviewed By: pdillinger
Differential Revision: D47536962
Pulled By: ajkr
fbshipit-source-id: bbee0fc4ad67fc699a66b8f2b4ea4544dd003691