Cloud releases: Switch to firstboot_pkg_upgrade

[ziaee]

Summary

Cloud images are deployed with base system packages. Introduce a firstboot package auto updater to patch the base system on first boot.

MFC after: 1 hour
MFC to: stable/15
Sponsored by: Google Cloud

[cperciva]

This is probably all you want, unless you want to also restrict the updates to FreeBSD-base. That's what I'll be doing in EC2; I don't want to risk things breaking if e.g. something happens with the python port.

This shouldn't be MFCed to stable/14 because we're not using pkgbase there.

Yes, we should do the other cloud images as well. I want to test in EC2 though.

[ziaee]

fix

[cperciva]

release/tools/azure.conf

46

firstboot_pkg_upgrade_repos

release/tools/ec2-base.conf

18

firstboot_pkg_upgrade

[ziaee]

fix typos, thanks @cperciva!

[cperciva]

release/tools/gce.conf

49

Did you mean to delete this line?

[ziaee]

fix lazy line reuse ^.^ thanks @cperciva!

[ziaee]

fix