Use variable names directly in the format strings (#7906)

# Description

Lint: `clippy::uninlined_format_args`

More readable in most situations.
(May be slightly confusing for modifier format strings
https://doc.rust-lang.org/std/fmt/index.html#formatting-parameters)

Alternative to #7865

# User-Facing Changes

None intended

# Tests + Formatting

(Ran `cargo +stable clippy --fix --workspace -- -A clippy::all -D
clippy::uninlined_format_args` to achieve this. Depends on Rust `1.67`)

crates/nu-command/src/default_context.rs

@@ -495,7 +495,7 @@ pub fn create_default_context() -> EngineState {
     };
 
     if let Err(err) = engine_state.merge_delta(delta) {
-        eprintln!("Error creating default context: {:?}", err);
+        eprintln!("Error creating default context: {err:?}");
     }
 
     engine_state