Use yum instead of dnf on Amazon Linux 2

[ConnorJC3]

Amazon Linux 2 only has yum, not dnf in the official AMIs. Thus, the kops-configuration service gets stuck on AL2 trying (and failing) to use dnf instead of yum.

This PR updates HasDNF to always return false for AL2 nodes.

[hakman]

Thanks @ConnorJC3, periodic tests indeed fail due to missing dnf:

W0813 18:08:52.913559    2659 executor.go:141] error running task "Package/conntrack-tools" (8m57s remaining to succeed): error installing package "conntrack-tools": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913570    2659 executor.go:141] error running task "Package/logrotate" (8m57s remaining to succeed): error installing package "logrotate": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913576    2659 executor.go:141] error running task "Package/libtool-ltdl" (8m57s remaining to succeed): error installing package "libtool-ltdl": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913584    2659 executor.go:141] error running task "Package/ethtool" (8m57s remaining to succeed): error installing package "ethtool": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913592    2659 executor.go:141] error running task "Package/chrony" (8m57s remaining to succeed): error installing package "chrony": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913597    2659 executor.go:141] error running task "Package/util-linux" (8m57s remaining to succeed): error installing package "util-linux": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913605    2659 executor.go:141] error running task "Package/libcgroup" (8m57s remaining to succeed): error installing package "libcgroup": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913611    2659 executor.go:141] error running task "Package/iptables" (8m57s remaining to succeed): error installing package "iptables": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913616    2659 executor.go:141] error running task "Package/libseccomp" (8m57s remaining to succeed): error installing package "libseccomp": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913624    2659 executor.go:141] error running task "Package/socat" (8m57s remaining to succeed): error installing package "socat": fork/exec /usr/bin/dnf: no such file or directory:
W0813 18:08:52.913631    2659 executor.go:141] error running task "Package/ebtables" (8m57s remaining to succeed): error installing package "ebtables": fork/exec /usr/bin/dnf: no such file or directory:

[hakman]

/test pull-kops-aws-distro-amazonlinux2
/test pull-kops-e2e-k8s-gce-cilium

[hakman]

The PR fixes the packages install part, but seems that newer containerd cannot run:

Starting containerd container runtime...
/usr/bin/containerd: /lib64/libc.so.6: version `GLIBC_2.32' not found (required by /usr/bin/containerd)
/usr/bin/containerd: /lib64/libc.so.6: version `GLIBC_2.34' not found (required by /usr/bin/containerd)
containerd.service: main process exited, code=exited, status=1/FAILURE

[hakman]

/test pull-kops-aws-distro-amazonlinux2

[hakman]

Thanks @ConnorJC3, looks like downgrading containerd worked.
/lgtm
/approve

[k8s-ci-robot]

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