Revert "CI: Build VTest with clang"

The issue with VTest not building properly in gcc is fixed since commit
vtest/VTest@0730540c43a2a23436b43f46327d6bac644d816d. Revert the patch to keep
the CI configuration simple.

This reverts commit e61f53eb44a390f9a8c8c4f34077c365942e0729.
2 files changed