Enable clippy::redundant_locals (#8750)

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

Release Notes:

- N/A

tooling/xtask/src/main.rs

@@ -111,7 +111,6 @@ fn run_clippy(args: ClippyArgs) -> Result<()> {
         "clippy::option_map_unit_fn",
         "clippy::redundant_closure_call",
         "clippy::redundant_guards",
-        "clippy::redundant_locals",
         "clippy::reversed_empty_ranges",
         "clippy::single_range_in_vec_init",
         "clippy::suspicious_to_owned",