Fix cursor overlap (#21999)

When the cursor has a block shape and is not on the first line, its name
popup exhibits an overlap:
<img width="171" alt="Screenshot 2024-12-13 at 18 00 54"
src="https://github.com/user-attachments/assets/1dc2ef93-020b-45c4-9fc6-db7d97f65c62"
/>

This occurs because the popup's horizontal alignment is set differently
when the cursor
[is](https://github.com/zed-industries/zed/blob/fff12ec1e5278e1825d912241f62179387ac8176/crates/editor/src/element.rs#L6383)
or
[isn't](https://github.com/zed-industries/zed/blob/fff12ec1e5278e1825d912241f62179387ac8176/crates/editor/src/element.rs#L6385)
on the first line.

This PR makes the horizontal alignment the same in both cases, which
removes the overlap:
<img width="176" alt="Screenshot 2024-12-13 at 17 57 20"
src="https://github.com/user-attachments/assets/a3c10ed5-6a1b-4040-9408-92290e9da30b"
/>

Closes #21887.

Release Notes:

- Fixed an overlap that cuts off user names when a cursor has a block
shape.