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/state-machine/src/basic.rs

@@ -82,8 +82,8 @@ impl BasicExternalities {
 	) -> R {
 		let mut ext = Self {
 			inner: Storage {
-				top: std::mem::replace(&mut storage.top, Default::default()),
-				children_default: std::mem::replace(&mut storage.children_default, Default::default()),
+				top: std::mem::take(&mut storage.top),
+				children_default: std::mem::take(&mut storage.children_default),
 			},
 			extensions: Default::default(),
 		};