chore!: BREAKING CHANGE: vector_db_id -> vector_store_id

# What does this PR do?


## Test Plan

docs/static/deprecated-llama-stack-spec.yaml

@@ -3252,7 +3252,7 @@ components:
           description: Type of the step in an agent turn.
           const: memory_retrieval
           default: memory_retrieval
-        vector_db_ids:
+        vector_store_ids:
           type: string
           description: >-
             The IDs of the vector databases to retrieve context from.
@@ -3265,7 +3265,7 @@ components:
         - turn_id
         - step_id
         - step_type
-        - vector_db_ids
+        - vector_store_ids
         - inserted_context
       title: MemoryRetrievalStep
       description: >-