Stop trying to pin package versions in the kicbase Dockerfile

[afbjorklund]

It doesn't work to pin the package versions, without also pinning all the apt packages (in a separate download somewhere)

# specify version of everything explicitly using 'apt-cache policy'
RUN apt-get update && apt-get install -y --no-install-recommends \
    lz4=1.9.1-1 \
    gnupg=2.2.12-1ubuntu3 \ 
    sudo=1.8.27-1ubuntu4.1 \
    docker.io=19.03.2-0ubuntu1 \
    openssh-server=1:8.0p1-6build1 \
    dnsutils=1:9.11.5.P4+dfsg-5.1ubuntu2.1 \
    # libglib2.0-0 is required for conmon, which is required for podman
    libglib2.0-0=2.62.1-1 \
    && rm /etc/crictl.yaml

As long as we are using latest/greatest ubuntu:eoan (or focal) anyway, we might as well just use apt-get install as well.

Trying to rebuild, and you get errors like:
E: Version '1:9.11.5.P4+dfsg-5.1ubuntu2.1' for 'dnsutils' was not found

This is due to security updates, since then.
https://packages.ubuntu.com/eoan/dnsutils

1:9.11.5.P4+dfsg-5.1ubuntu2.2 [security]: amd64 i386
1:9.11.5.P4+dfsg-5.1ubuntu2 [ports]: arm64 armhf ppc64el s390x 

This is of course a problem when it comes to reproducability, but that is something that is being shared with upstream KIND.

If you try to rebuild the docker old image now, you get a different result than the binary that is posted on the Docker Hub:

kindest_base.diff.txt

So we should focus on package names, and then use ranges where it matters.

[afbjorklund]

Same problem in #7884

[afbjorklund]

See #8251 (comment)