Remove FlexibleCollections feature flag logic for repository methods:
* GetManyByUserIdAsync
* GetManyByUserIdCipherIdAsync
* UpdateCollectionsAsync
* UpdateCollectionsForCiphersAsync
This feature flag was never turned on and we will update the sprocs
directly as required.
* [PM-2383] Add bulk add/remove collection cipher repository methods
* [PM-2383] Add additional authorization helpers for CiphersControlle
* [PM-2383] Add /bulk-collections endpoint to CiphersController.cs
* [PM-2383] Add EF implementation for new CollectionCipherRepository methods
* [PM-2383] Ensure V1 logic only applies when the flag is enabled for new bulk functionality
