Use mem::take instead of mem::replace where appropriate (#5846)

* replace replace with take

* Update client/api/src/cht.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update client/api/src/cht.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/primitives/core/src/offchain/testing.rs

@@ -105,7 +105,7 @@ impl OffchainState {
 	fn fulfill_expected(&mut self, id: u16) {
 		if let Some(mut req) = self.expected_requests.remove(&RequestId(id)) {
 			let response = req.response.take().expect("Response checked while added.");
-			let headers = std::mem::replace(&mut req.response_headers, vec![]);
+			let headers = std::mem::take(&mut req.response_headers);
 			self.fulfill_pending_request(id, req, response, headers);
 		}
 	}