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/group_by.rs

@@ -10,7 +10,7 @@ fn groups() {
             r#"
                 first_name,last_name,rusty_at,type
                 Andrés,Robalino,10/11/2013,A
-                Jonathan,Turner,10/12/2013,B
+                JT,Turner,10/12/2013,B
                 Yehuda,Katz,10/11/2013,A
             "#,
         )]);
@@ -39,7 +39,7 @@ fn errors_if_given_unknown_column_name() {
                     "nu": {
                         "committers": [
                             {"name": "Andrés N. Robalino"},
-                            {"name": "Jonathan Turner"},
+                            {"name": "JT Turner"},
                             {"name": "Yehuda Katz"}
                         ],
                         "releases": [
@@ -79,7 +79,7 @@ fn errors_if_block_given_evaluates_more_than_one_row() {
             r#"
                 first_name,last_name,rusty_at,type
                 Andrés,Robalino,10/11/2013,A
-                Jonathan,Turner,10/12/2013,B
+                JT,Turner,10/12/2013,B
                 Yehuda,Katz,10/11/2013,A
             "#,
         )]);