Update copy for null state of secondary tabs

carets < > around description should not appear. They were just placeholders to indicate the text was variable (:

Remove the word "is" from the text. It's not logical when the tab is plural such as "stem cell characteristics". Removing it work for each circumstance.

<img width="775" height="84" alt="Image" src="https://github.com/user-attachments/assets/522484d8-f3f9-4893-931d-0e5fe3b9ccc7" />