Remove the requirement for shallow pit for junk metal walls

[MrLostman]

Summary

SUMMARY: Balance "Remove the requirement for shallow pit for junk metal walls"

Purpose of change

To allow players to construct their dream slum.

Describe the solution

The requirement for shallow pits means junk metal walls can only be built on dirt tiles this substantially limits their use. There is no makeshift wall that can be used on floor tiles and the junk metal walls are an excellent fill for this roll.

Testing

1. constructed, deconstructed & smashed the wall
2. tested building in different spots to make sure there wasn't any unwanted behavior

Additional context

[scarf005]

checked

i don't see why junk walls cannot be constructed on floor. the tiles look a bit weird, tho.

digging requirement changes on faction camp also works as intended.