if --no-config-file(-n) is passed, do not load config files with -c (#9286)

# Description

I noticed recently these timing discrepancies. I was thinking they would
be nearly identical but they were not.
```
> nu --no-std-lib -n -c "$nu.startup-time"
13ms 686µs 209ns
> nu --no-std-lib -n
> $nu.startup-time
2ms 520µs 416ns
```
My research showed that if `-n` was passed with `-c`, then the `-n` was
essentially being ignored. This PR corrects that.

Also worthy of understanding, if `nu -c "some command"` is passed, the
default env file is always loaded. I believe that's on purpose so that a
NU_LIB_DIRS env is available.

## After this PR (on a different system)
```
> nu --no-std-lib -n -c "$nu.startup-time"
6ms 688µs 600ns
> nu -n --no-std-lib
> $nu.startup-time
6ms 661µs 800ns
```

# User-Facing Changes
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src/run.rs

@@ -21,6 +21,12 @@ pub(crate) fn run_commands(
     let mut stack = nu_protocol::engine::Stack::new();
     let start_time = std::time::Instant::now();
 
+    // if the --no-config-file(-n) option is NOT passed, load the plugin file,
+    // load the default env file or custom (depending on parsed_nu_cli_args.env_file),
+    // and maybe a custom config file (depending on parsed_nu_cli_args.config_file)
+    //
+    // if the --no-config-file(-n) flag is passed, do not load plugin, env, or config files
+    if parsed_nu_cli_args.no_config_file.is_none() {
         #[cfg(feature = "plugin")]
         read_plugin_file(
             engine_state,
@@ -40,7 +46,12 @@ pub(crate) fn run_commands(
         let start_time = std::time::Instant::now();
         // only want to load config and env if relative argument is provided.
         if parsed_nu_cli_args.env_file.is_some() {
-        config_files::read_config_file(engine_state, &mut stack, parsed_nu_cli_args.env_file, true);
+            config_files::read_config_file(
+                engine_state,
+                &mut stack,
+                parsed_nu_cli_args.env_file,
+                true,
+            );
         } else {
             config_files::read_default_env_file(engine_state, &mut stack)
         }
@@ -70,7 +81,7 @@ pub(crate) fn run_commands(
             column!(),
             use_color,
         );
-
+    }
     // Before running commands, set up the startup time
     engine_state.set_startup_time(entire_start_time.elapsed().as_nanos() as i64);
     let start_time = std::time::Instant::now();