fix(ui2): dropdown button overlap (#103404)

Very minor fix! The dropdown trigger on these buttons had a `2px`
divider when it should be `1px`. The fix is setting `margin-left: -1px`
to overlap the elements.

Check the **Resolve** and **Archive** buttons below.

| | Light | Dark |
|--------|--------|--------|
| **Before** | <img width="1510" height="180"
alt="before-light-issue-stream-action"
src="https://github.com/user-attachments/assets/38d45912-6745-4f5a-a06d-8bc49264fa11"
/> | <img width="1510" height="180"
alt="before-dark-issue-stream-action"
src="https://github.com/user-attachments/assets/53b447ac-3089-4f61-9826-545b11419490"
/> |
| **After** | <img width="1510" height="180"
alt="after-light-issue-stream-action png"
src="https://github.com/user-attachments/assets/6742a4ca-d7be-4dd4-ad4b-4216cf0db969"
/> | <img width="1510" height="180" alt="after-dark-issue-stream-action"
src="https://github.com/user-attachments/assets/a99aa8b5-8352-4b3d-8e11-7e5ade2658f2"
/> |

Author: natemoo-re

static/app/components/dropdownMenu/index.tsx

@@ -293,4 +293,7 @@ export {DropdownMenu};
 const DropdownMenuWrap = styled('div')`
   display: contents;
   list-style-type: none;
+  > :first-child {
+    margin-left: -1px;
+  }
 `;