Move to using a safer shell integration default setting (#9600)

# Description

We're seeing some issues in a few terminals with the shell integration
support. Moving shell_integration to off by default to help with the
default user experience, but it will remain easy to re-enable for folks
who want to have the integration experience and a terminal that supports
it well.

# User-Facing Changes

This turns off shell integration by default, requiring the user to edit
the config and re-enable it.

# Tests + Formatting
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crates/nu-utils/src/sample_config/default_config.nu

@@ -307,7 +307,7 @@ $env.config = {
   use_ansi_coloring: true
   bracketed_paste: true # enable bracketed paste, currently useless on windows
   edit_mode: emacs # emacs, vi
-  shell_integration: true # enables terminal markers and a workaround to arrow keys stop working issue
+  shell_integration: false # enables terminal shell integration. Off by default, as some terminals have issues with this.
   render_right_prompt_on_last_line: false # true or false to enable or disable right prompt to be rendered on last line of the prompt.
 
   hooks: {