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

Summary:
In #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: #45263

Test Plan: repeat request given in #44483

Reviewed By: cortinico

Differential Revision: D59364609

Pulled By: dmytrorykun

fbshipit-source-id: 2a8b86c526320a1e9c1c58e41aa9c74beeeac2ce

packages/react-native/Libraries/Network/RCTNetworking.mm

@@ -365,6 +365,12 @@ - (RCTURLRequestCancellationBlock)buildRequest:(NSDictionary<NSString *, id> *)q
                                       forHTTPHeaderField:@"Content-Length"];
                                 }
 
+                                // NSRequest default cache policy violate on `If-None-Match`, should allow the request
+                                // to get 304 from server.
+                                if (request.allHTTPHeaderFields[@"If-None-Match"]) {
+                                  request.cachePolicy = NSURLRequestReloadIgnoringLocalCacheData;
+                                }
+
                                 dispatch_async([self requestQueue], ^{
                                   block(request);
                                 });