CarpetX: a Cactus driver for the Einstein Toolkit based on AMReX

CarpetX: reverted an if...else change The else was functionally unnecessary, and the original code did not use else. The reversion makes comparison of changes easier for reviewers. This commit also includes the clang-format changes, which are purely cosmetic.

Created by  Samuel Cupp  on October 21, 2020
E7WUAZCMU5IUJMF4SPNX3CDXGZACKOJDQBH2DHVJXWUQH3ULQGJQC
Change contents