Auto merge of #29752 - mrobinson:fix-29741-by-extending-request-builder, r=mukilan

Fix 29741 by extending request builder

Extend RequestBuilder to include ResponseTainting and used said functionality to set response_tainting to `::CorsTainting` in `cors_preflight_fetch()`.

---
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- [x] These changes fix #29741
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components/script/fetch.rs

@@ -127,6 +127,7 @@ fn request_init_from_request(request: NetTraitsRequest) -> RequestBuilder {
         initiator: request.initiator,
         csp_list: None,
         https_state: request.https_state,
+        response_tainting: request.response_tainting,
     }
 }