Apply nightly clippy lints (#9654)

# Description
- A new one is the removal of unnecessary `#` in raw strings without `"`
inside.
-
https://rust-lang.github.io/rust-clippy/master/index.html#/needless_raw_string_hashes
- The automatically applied removal of `.into_iter()` touched several
places where #9648 will change to the use of the record API. If
necessary I can remove them @IanManske to avoid churn with this PR.
- Manually applied `.try_fold` in two places
- Removed a dead `if`
- Manual: Combat rightward-drift with early return

crates/nu-cmd-dataframe/src/dataframe/eager/sql_context.rs

@@ -150,7 +150,7 @@ impl SQLContext {
             let agg_df = df.groupby(group_by).agg(agg_projection);
             let mut final_proj_pos = groupby_pos
                 .into_iter()
-                .chain(agg_proj_pos.into_iter())
+                .chain(agg_proj_pos)
                 .collect::<Vec<_>>();
 
             final_proj_pos.sort_by(|(proj_pa, _), (proj_pb, _)| proj_pa.cmp(proj_pb));