[style] update dropdown button text class in Vue node upload widgets (#6062)

## Summary

Change colors to match Figma variables.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6062-style-update-dropdown-button-text-class-in-Vue-node-upload-widgets-28c6d73d365081ae8857ddcef06784ef)
by [Unito](https://www.unito.io)

---------

Co-authored-by: github-actions <github-actions@github.com>

src/renderer/extensions/vueNodes/widgets/components/form/dropdown/FormDropdownInput.vue

@@ -33,16 +33,20 @@ const selectedItems = computed(() => {
 })
 
 const chevronClass = computed(() =>
-  cn('mr-2 size-4 transition-transform duration-200 flex-shrink-0', {
-    'rotate-180': props.isOpen
-  })
+  cn(
+    'mr-2 size-4 transition-transform duration-200 flex-shrink-0 text-button-icon',
+    {
+      'rotate-180': props.isOpen
+    }
+  )
 )
 
 const theButtonStyle = computed(() =>
-  cn('bg-transparent border-0 outline-none text-zinc-400', {
+  cn('bg-transparent border-0 outline-none text-text-secondary', {
     'hover:bg-node-component-widget-input-surface/30 cursor-pointer':
       !props.disabled,
-    'cursor-not-allowed': props.disabled
+    'cursor-not-allowed': props.disabled,
+    'text-text-primary': selectedItems.value.length > 0
   })
 )
 </script>