chore: allow make docker-generate to work with SELINUX

[jvillal-amp]

Without this change when running on a system using SELINUX you will
receive an error like this:

<snip>
ts=2023-11-27T15:48:48.150Z caller=net_snmp.go:175 level=info msg="Loading MIBs" from=mibs
ts=2023-11-27T15:48:48.150Z caller=main.go:134 level=error msg="Error generating config netsnmp" err="unable to determine absolute path for output"
make: *** [Makefile:92: docker-generate] Error 1

Information on the ':Z' option at:
https://docs.docker.com/storage/bind-mounts/#configure-the-selinux-label

[SuperQ]

Can you provide a little more description of why this is needed?

[jvillal-amp]

Can you provide a little more description of why this is needed?

Done @SuperQ

Thanks.

[hhromic]

This part in the linked documentation is a bit scary:

Use extreme caution with these options. Bind-mounting a system directory such as /home or /usr with the Z option renders your host machine inoperable and you may need to relabel the host machine files by hand.

I know is a bit late (this PR was already merged), but doing it like etcd does wouldn't be a safer approach?

https://github.com/kubernetes/kubernetes/blob/ad9b60e2c9ddb21e8b00cabbe27e639638a0ea88/cluster/images/etcd/Makefile#L76-L81

Note that they use :z instead of :Z.
Disclaimer: I am not a user of SELinux and I am not super familiar with these options and their implications.

[SuperQ]

@hhromic Yea, I agree, I should have read the Docker documentation more closely. Would you mind opening a fix PR?

[hhromic]

Sure, I will open a PR with that approach. 👍
I hope @jvillal-amp can confirm if using :z instead of :Z solves the issue for them.