thorium_node: fix regression added in 47a651c857

Link: https://github.com/GeneAssembly/biosal/issues/795
Link: https://github.com/GeneAssembly/biosal/issues/796
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium_worker: simplify random seed

Link: https://github.com/GeneAssembly/biosal/issues/794
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>