[fix] improve FormDropdownMenu scrolling behavior (#6570)

This pull request makes a minor UI adjustment to the
`FormDropdownMenu.vue` component. The change improves the dropdown
menu's usability by allowing its contents to scroll vertically and adds
a small top margin for better spacing.

* UI improvement: Changed the dropdown list container to use
`overflow-y-scroll` and added a top margin (`mt-2`) for improved
scrolling and spacing.
(`src/renderer/extensions/vueNodes/widgets/components/form/dropdown/FormDropdownMenu.vue`)-
Add top margin (mt-2) for better spacing
- Change overflow-hidden to overflow-y-scroll for scrollable list

## Current

https://github.com/user-attachments/assets/40cb4600-ff4e-41a5-89d6-a9aee48fa633

## Before


https://github.com/user-attachments/assets/fbe7a399-06d5-4cda-b850-f28b09f20d73

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6570-fix-improve-FormDropdownMenu-scrolling-behavior-2a16d73d3650815c883fcfeb7d9a3ace)
by [Unito](https://www.unito.io)

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

@@ -53,7 +53,7 @@ const searchQuery = defineModel<string>('searchQuery')
       :is-querying="isQuerying"
     />
     <!-- List -->
-    <div class="relative flex h-full overflow-hidden">
+    <div class="relative flex h-full mt-2 overflow-y-scroll">
       <div
         :class="
           cn(