chore: remove createStore option

docs/react/guides/migrating-to-v5.md

@@ -443,16 +443,4 @@ Note that the infinite list must be bi-directional, which requires both `getNext
 
 See the [Typescript Docs](../typescript#typing-query-options) for more details.
 
-### CreateStore
-
-We are now exposing a way to customize how queries are stored internally. Per default, a `Map` is used but, with the new `createStore` function, you can now use any data structure you want.
-
-```ts
-const queryClient = new QueryClient({
-  queryCache: new QueryCache({
-    createStore: () => new Map()
-  }),
-})
-```
-
 [//]: # 'NewFeatures'

docs/react/reference/QueryCache.md

@@ -43,9 +43,6 @@ Its available methods are:
 - `onSettled?:` (data: unknown | undefined, error: unknown | null, query: Query) => void
   - Optional
   - This function will be called if some query is settled (either successful or errored).
-- `createStore?: () => QueryStore`
-  - Optional
-  - This function will be called to create the store that will be used to store the queries. By default, a `Map` is used.
 
 ## Global callbacks
 

packages/query-core/src/queryCache.ts

@@ -27,7 +27,6 @@ interface QueryCacheConfig {
     error: DefaultError | null,
     query: Query<unknown, unknown, unknown>,
   ) => void
-  createStore?: () => QueryStore
 }
 
 interface NotifyEventQueryAdded extends NotifyEvent {
@@ -95,7 +94,7 @@ export class QueryCache extends Subscribable<QueryCacheListener> {
 
   constructor(public config: QueryCacheConfig = {}) {
     super()
-    this.#queries = config.createStore?.() ?? new Map<string, Query>()
+    this.#queries = new Map<string, Query>()
   }
 
   build<TQueryFnData, TError, TData, TQueryKey extends QueryKey>(

packages/query-core/src/tests/queryCache.test.tsx

@@ -329,23 +329,6 @@ describe('queryCache', () => {
     })
   })
 
-  describe('QueryCacheConfig.createStore', () => {
-    test('should call createStore', async () => {
-      const createStore = vi.fn().mockImplementation(() => new Map())
-      new QueryCache({ createStore })
-      expect(createStore).toHaveBeenCalledWith()
-    })
-
-    test('should use created store', async () => {
-      const store = new Map()
-      const spy = vi.spyOn(store, 'get')
-
-      new QueryCache({ createStore: () => store }).get('key')
-
-      expect(spy).toHaveBeenCalledTimes(1)
-    })
-  })
-
   describe('QueryCache.add', () => {
     test('should not try to add a query already added to the cache', async () => {
       const key = queryKey()