fix: on iOS not getting 304 from `If-None-Match` request (#45263)

Summary:
In https://github.com/facebook/react-native/issues/44483 `If-None-Match` request failed to get a 304 after a 200 response. This is caused by NSRequest's
cachePolicy which prevents sending a request to server to check 304 state and return directly a 200 response.

## Changelog:

[IOS] [FIXED] - fix: on iOS not getting 304 from `If-None-Match` request

Pull Request resolved: https://github.com/facebook/react-native/pull/45263

Test Plan: repeat request given in https://github.com/facebook/react-native/issues/44483

Reviewed By: cortinico

Differential Revision: D59364609

Pulled By: dmytrorykun

fbshipit-source-id: 2a8b86c526320a1e9c1c58e41aa9c74beeeac2ce