Removes old references to scattering_potential.cpp(h) somehow leftove…

[bHimes]

…r in programs/simulate after moving scattering_potential into the core library.

Description

Deleted code is not currently referenced. This is just a cleanup to avoid potential confusion in the future.

Fixes # (issue)

I have rebased my feature branch to be current with the master branch using to minimize conflicts and headaches

• [x] yes
• [ ] no

Which compilers were tested

• [ ] g++
• [X] icpc
• [ ] clang
• [ ] other (please specify)

These changes are isolated to the

• [ ] gui
• [ ] core library
• [ ] gpu core library
• [X] program it modifies

How has the functionality been tested?

Please describe the tests that you ran to verify your changes. Please also note any relevant details for your test configuration.

• [ ] Tested manually from GUI
• [ ] Tested manually from CLI
• [ ] Passed console tests
• [ ] Passed samples functional testing
• [X] none

Checklist:

• [X] I have not changed anything that did not need to be changed
• [X] I have performed a self-review of my own code
• [ ] I have commented my code, (w.r.t. why), particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation {Ok to pass for now}
• [X] My changes generate no new warnings
• [X] Any dependent changes have been merged and published in downstream modules

[bHimes]

@kekexinz tagging you for review just incase you have any older branches that might be referencing this now deleted code.