Fix warnings and old names (#8457)

# Description

This fixes up some clippy warnings and removes some old names/info from
our unit tests

# User-Facing Changes

Internal changes only

# Tests + Formatting

Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
- `cargo test --workspace` to check that all tests pass

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```

# After Submitting

If your PR had any user-facing changes, update [the
documentation](https://github.com/nushell/nushell.github.io) after the
PR is merged, if necessary. This will help us keep the docs up to date.

crates/nu-command/tests/commands/rename.rs

@@ -9,7 +9,7 @@ fn changes_the_column_name() {
             "los_cuatro_mosqueteros.txt",
             r#"
                 Andrés N. Robalino
-                Jonathan Turner
+                JT Turner
                 Yehuda Katz
                 Jason Gedge
             "#,
@@ -38,7 +38,7 @@ fn keeps_remaining_original_names_given_less_new_names_than_total_original_names
             "los_cuatro_mosqueteros.txt",
             r#"
                 Andrés N. Robalino
-                Jonathan Turner
+                JT Turner
                 Yehuda Katz
                 Jason Gedge
             "#,
@@ -68,7 +68,7 @@ fn errors_if_no_columns_present() {
             "los_cuatro_mosqueteros.txt",
             r#"
                 Andrés N. Robalino
-                Jonathan Turner
+                JT Turner
                 Yehuda Katz
                 Jason Gedge
             "#,
@@ -94,7 +94,7 @@ fn errors_if_columns_param_is_empty() {
             "los_cuatro_mosqueteros.txt",
             r#"
                 Andrés N. Robalino
-                Jonathan Turner
+                JT Turner
                 Yehuda Katz
                 Jason Gedge
             "#,