Move the reasons of trhead unsafety to the lines of ATLAS_NOT_THREAD_SAFE or ATLAS_NO_CHECK_FILE_THREAD_SAFETY for easier understanding using LXR and git grep. Remove ATLAS_NOT_THREAD_SAFE from TRT_BSErrContainerCnv_p1::transToPers and TRT_BSErrContainerCnv_p2::transToPers.