Level Editor layout is wonky

[faucomte97]

Describe the bug The Level Editor layout has become wonky. The grid has grown in size so it no longer fits in the window and the bin has moved closer to the centre of the window. Additionally, when moving scenery assets onto the grid, the mouse cursor isn't in line with the grid and where the asset actually ends up - most likely a byproduct of the grid being oversized.

This is a side-effect of #1516. Reverting the code to what it was before that change "fixes" it, although the original issue comes back whereby the grid is cut off. A solution needs to be found to fix both problems.

To Reproduce Steps to reproduce the behaviour:

1. Go to the level editor.
2. Notice that the grid no longer fits in the window and the bin isn't in the bottom-right corner anymore.
3. Click on the "Scenery" tab on the side.
4. Click on any scenery asset.
5. Drag the asset from the corner of the grid to any point of the grid and notice that where your cursor is doesn't match where the asset ends up.

Expected behaviour The grid should fit within the window and the bin should go back to the bottom-right of the window. Assets that are added to the map should be in line with where the cursor is.

Screenshots

Desktop (please complete the following information): Probably all (double-check)