Fix overflow to show grouped builds arrow

## What does this MR do?
Removes overflow style so that the arrow shows up again

## Screenshots (if relevant)
Before:   
![Screen_Shot_2016-10-11_at_9.11.55_AM](/uploads/92d2a0c34d2af050e58468c8d61f4cd3/Screen_Shot_2016-10-11_at_9.11.55_AM.png)
After:   
![Screen_Shot_2016-10-11_at_9.11.41_AM](/uploads/2c4c422a21fb6450d00ae638aef29d89/Screen_Shot_2016-10-11_at_9.11.41_AM.png)
Scrolling:   
![Screen_Shot_2016-10-11_at_9.40.36_AM](/uploads/e5b1e3125d881c5882cf199026110d48/Screen_Shot_2016-10-11_at_9.40.36_AM.png)

See merge request !6808