[Tests] Set DOT_NUM_THREADS and force clean workspace to make the doxygen test and the container test more robust.#6906

mohanchen merged 5 commits intodevelopdeepmodeling/abacus-develop:developfrom

ZhouXY-PKU-patch-dotcontdeepmodeling/abacus-develop:ZhouXY-PKU-patch-dotcontCopy head branch name to clipboard