Implement explosive trap +-30% base tertiary radius, fix overlap chance for transfigured version

[Edvinas-Smita]

Fixes #6909 and #7260 . Supersedes #7321 .

Description of the problem being solved:

Explosive Trap of Shrapnel was using wrong variables for it's overlap calculations and producing incorrect values. The +- 30% base radius on both explosive traps was not yet implemented leading to overestimating the damage output.

Steps taken to verify a working solution:

• The "Average explosions hitting" setting produces a bit lower overlap chance for normal version and not 100% for trans version

Link to a build that showcases this PR:

https://pobb.in/HFrrt77bxIjn

Before screenshots:

After screenshots: