Everywhere: Remove instances of clippy::redundant-clone (#43212)

This change fixes all instances where
[`clippy::redundant-clone`](https://rust-lang.github.io/rust-clippy/master/index.html?groups=complexity%2Ccorrectness%2Cnursery%2Csuspicious&levels=allow#redundant_clone)
would trigger. It's allowed by default

I've also changed the lint to warn-by-default for servo.

Testing: Covered by WPT

---------

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

components/script/dom/css/cssstyledeclaration.rs

@@ -183,8 +183,7 @@ impl CSSStyleOwner {
                     .url_data
                     .0
                     .clone()
-            })
-            .clone(),
+            }),
         }
     }
 }