Fixes the padding of the "notes" button in collab-ui. I'm not sure why
the previous code used `div().h_7().w_full()`. Am I missing something
here?

### Before
![Screenshot 2024-02-02 at 15 26
44](https://github.com/zed-industries/zed/assets/53836821/0577b706-b433-4e02-802b-b6eccefb3acd)

### After
![Screenshot 2024-02-02 at 15 27
26](https://github.com/zed-industries/zed/assets/53836821/00fd81d8-82a1-4936-829c-022554259fd5)



Release Notes:
- Fixed padding of the "notes" button in the collaboration panel.

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>