fix right prompt in the default_env.nu (#9581)

# Description

## Before

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## After

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crates/nu-utils/src/sample_config/default_env.nu

@@ -25,14 +25,13 @@ def create_left_prompt [] {
 }
 
 def create_right_prompt [] {
-    let time_segment_color = (ansi magenta)
-
+    # create a right prompt in magenta with green separators and am/pm underlined
     let time_segment = ([
         (ansi reset)
-        $time_segment_color
+        (ansi magenta)
         (date now | date format '%m/%d/%Y %r')
-    ] | str join | str replace --all "([/:])" $"(ansi light_magenta_bold)${1}($time_segment_color)" |
-        str replace --all "([AP]M)" $"(ansi light_magenta_underline)${1}")
+    ] | str join | str replace --all "([/:])" $"(ansi green)${1}(ansi magenta)" |
+        str replace --all "([AP]M)" $"(ansi magenta_underline)${1}")
 
     let last_exit_code = if ($env.LAST_EXIT_CODE != 0) {([
         (ansi rb)