bug: random levels default to grass scenery instead of user's choice

[evemartin]

Describe the bug
In the Level Editor, whenever the user generates a random level, it always defaults to grass scenery even when the user has chosen a different scenery theme beforehand.

To Reproduce
Steps to reproduce the behaviour:

1. Go to the Level Editor
2. Go to the Scenery tab and change the scenery to a different theme (i.e. snow)
3. Go to the Random tab and click Generate. Notice that the scenery automatically changes back to grass when the level is generated

Expected behaviour
Instead of defaulting back to grass, the scenery of a randomly generated level should always match the current theme.

Screenshots

Screencast.from.05-09-24.14.07.21.webm