Fix bottom position of scroll buttons in build log page

Look at the up/down buttons as well as the **Enable Autoscroll**.

The **Enable Autoscroll** could also be alligned with the right grey box.


## Before

![autoscroll_before](/uploads/f410dc353ca66c338d8a29c7c294758a/autoscroll_before.png)

## After

![autoscroll_after](/uploads/015fdf53618a0d6f468d666de1bbab6a/autoscroll_after.png)


\cc @dzaporozhets @creamzy 

See merge request !1792