Promote SecondaryNetwork feature to Beta

[luolanzone]

This is an issue to track the efforts or any per-requisites we should meet to promote SecondaryNetwork feature to Beta.

[luolanzone]

cc @tnqn @antoninbas @jianjuns

[antoninbas]

@luolanzone we haven't created the corresponding issues, but we still have a few key items to handle before we can graduate the feature. For example, we still need to address this:

although one thing that bothers me is that when we restore the cniCache we do not have the netNS: https://github.com/antrea-io/antrea/pull/6853/files#diff-e0583a662ecd5a62276021c7d81465dd15a0e35b33ec709e317e3644b6d89f25R572-R574. So the cniCache is not in the same state after a restart, and that will be an issue for a few things: support for SecondaryNetwork updates, or if the Agent was restarted before the secondary interfaces were created.

and more generally, we need to support SecondaryNetwork updates (e.g., a network interface is removed from the Pod)

[luolanzone]

Hi @antoninbas thanks for the info. I will check and create a sub-issue for it.
btw, I checked the doc, looks like we also need to promote AntreaIPAM as well if SecondaryNetwork is promoted? (it seems the only IPAM supported by SecondaryNetwork). Or it's actually OK to keep it as Alpha when SecondaryNetwork is Beta?

[luolanzone]

@tnqn I think we need a follow up document PR for SR-IOV support in #6881.