Changed icon, added translation

[snipe]

We were previously using a trash icon for the UI element to remove a custom field from a fieldset, which was mostly okay, but it could be confusing, since hitting the trash icon there doesn't delete the field itself, just the relationship with the fieldset. Switching to a "minus" symbol makes this a little clearer.

[what-the-diff]

PR Summary

• Introduction of a New Translation Key
  A new translation key named remove_customfield_association has been integrated into the language file general.php. This enhances our app's multilingual support, making it more accessible to a wider audience.

• Modification in User Interface Elements
  There have been visual modifications in the view.blade.php file. Specifically, both the tooltip and icon of a certain button have been altered. This change is intended to improve user experience, making interaction with the application more intuitive and efficient.