fix(dashboard): change delete instance form to use icon-only loading state

- replace 'Removendo...' text with icon-only loading style in delete instance confirmation
- align loading indicator with other form submission patterns

Author: luanmykel

internal/dashboard/templates/instances.tmpl

@@ -902,7 +902,7 @@ document.addEventListener('DOMContentLoaded', function() {
       );
       if (confirmed) {
         if (typeof setFormSubmittingState === 'function') {
-          setFormSubmittingState(this, { loadingText: 'Removendo...' });
+          setFormSubmittingState(this, { loadingStyle: 'icon' });
         }
         this.submit();
       }