Jenkinsfile: Drop NSS hack to please SSH
The Docker images for the build environment now ship the libnss-unknown plugin to work around the SSH/NSS issues at the system level, so we no longer need to carry the workaround here.
The Docker images for the build environment now ship the libnss-unknown plugin to work around the SSH/NSS issues at the system level, so we no longer need to carry the workaround here.