Drop explicitly setting `NB_EXE_TIMEOUT`
Drop explicitly setting `NB_EXE_TIMEOUT`

Simply rely on the timeout default set in the workflow tests for the
moment. Currently 30s is already the default timeout in the present
release of the workflow. It will bump up to 60s in the upcoming release.

nanshe-org/docker_nanshe_workflow,DudLab/docker_nanshe_workflow,DudLab/docker_nanshe_workflow,nanshe-org/docker_nanshe_workflow