hide ToggleCollapseButton when editing

apps/app/src/components/Sidebar/SidebarHead/ToggleCollapseButton.module.scss

@@ -1,6 +1,7 @@
 @use '@growi/core/scss/bootstrap/init' as bs;
 
 @use '~/styles/variables' as var;
+@use '~/styles/mixins';
 
 @use '../button-styles';
 
@@ -23,6 +24,14 @@
   }
 }
 
+// Hide when editing
+@include mixins.editing() {
+  .btn-toggle-collapse {
+    visibility: hidden;
+  }
+}
+
+
 // == Colors
 .btn-toggle-collapse {
   &:global {