Enable clippy::needless_update (#8830)

This PR enables the
[`clippy::needless_update`](https://rust-lang.github.io/rust-clippy/master/index.html#/needless_update)
rule and fixes the outstanding violations.

Release Notes:

- N/A

tooling/xtask/src/main.rs

@@ -93,7 +93,6 @@ fn run_clippy(args: ClippyArgs) -> Result<()> {
         "clippy::iter_overeager_cloned",
         "clippy::let_underscore_future",
         "clippy::map_entry",
-        "clippy::needless_update",
         "clippy::never_loop",
         "clippy::non_canonical_clone_impl",
         "clippy::non_canonical_partial_ord_impl",