images/baremetal: remove nss package as it's no longer needed

These images are failing to build internally for OSE due to missing the
nss wrapper package.

The underyling problem we are seeing when trying to use the
baremetal-installer image in CI to ssh to the packet server is that
user ID's are generated dynamically. This results in errors like this
when attempting to use SSH:

        No user exists for uid 102400000

The way most CI containers work around this is to echo a valid user to
/etc/passwd, as /etc/passwd is left writeable. The base images for
OpenShift now do this by default, so we can remove nss entirely.

images/baremetal/Dockerfile.ci

@@ -1,5 +1,5 @@
 # This Dockerfile is a used by CI to publish an installer image
-# It builds an image containing openshift-install, and nss mock.
+# It builds an image containing openshift-install.
 
 FROM registry.svc.ci.openshift.org/openshift/release:golang-1.13 AS builder
 RUN yum install -y libvirt-devel && \
@@ -11,11 +11,10 @@ RUN TAGS="libvirt baremetal" hack/build.sh
 
 FROM registry.svc.ci.openshift.org/origin/4.1:base
 COPY --from=builder /go/src/github.com/openshift/installer/bin/openshift-install /bin/openshift-install
-COPY --from=builder /go/src/github.com/openshift/installer/images/libvirt/mock-nss.sh /bin/mock-nss.sh
 
 RUN yum update -y && \
     yum install --setopt=tsflags=nodocs -y \
-    libvirt-libs nss_wrapper openssl unzip jq openssh-clients && \
+    libvirt-libs openssl unzip jq openssh-clients && \
     yum clean all && rm -rf /var/cache/yum/*
 
 RUN mkdir /output && chown 1000:1000 /output