Support Proxy in Ubuntu 22, 24 autoinstall

[vignesh-goutham]

When image builder is running in an air-gapped proxy available environment, the proxy configs http_proxy, https_proxy & no_proxy overrides are not used on the Ubuntu autoinstall, leading to failed OS install.

Adding proxy variables to the autoinstall should fix this issue.

/kind bug

[mohsenkamini]

If I am not mistaken, the Ubuntu auto install will fail if the VM has an IP address but not internet access(because it runs apt commands and they'll fail). I think we might consider fixing this too.

[sriramandev]

@vignesh-goutham / @mohsenkamini Which provider are we talking about here?

[mohsenkamini]

@vignesh-goutham / @mohsenkamini Which provider are we talking about here?

well my case was with prometheus. But I have experienced this issue across ESXi too(not as a provider for image-builder tho). I guess this is the default behaviour of ubuntu installer.