tab_switcher: Add placeholder text (#31697)

| Before | After |
|---|---|
|<img width="478" alt="image"
src="https://github.com/user-attachments/assets/5baba783-ee31-42cd-9760-7ee19edb1123"
/>|<img width="478" alt="image"
src="https://github.com/user-attachments/assets/1b149500-4a97-4085-80e5-fd628c92471a"
/>|

Release Notes:

- N/A
c57e6bc7845brian committed on 5/29/2025, 4:09:07 PM· committed by GitHubparent83135e9
1 file changedLine totals unavailable