google-compute-config.nix: fix comments, update google-*.service units, fix paths in gce

[flokli]

Motivation for this change

With local-fs.target part of sysinit.target
(#61321), we don't need to add it
explicitly to certain units anymore, and can change dependencies like
they are in other distros (I picked from Google's official CentOS 7
image here).

Like them, use StandardOutput=journal+console to pipe google-*.service
output to the serial console as well.

Update comment about ssh login and move enabling OS Login (together with
a comment) next to it

Remove a comment accidentially copied over from amazon-image.nix.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @

[flokli]

I tested this by successfully booting a new GCP instance based on this config.

The services still boot up. There's some missing shebangs in some scripts (which were before too, will update the google-compute-engine accordingly.

[flokli]

I patched shebangs and fixed paths. The scripts previously erroring into syslog are now properly executed.

We now set virtionet IRQ affinities, and local SSD parameters as well :-)

[flokli]

I also verified startup and shutdown scripts configured in metadata are properly executed:

	metadata {
        enable-oslogin = "TRUE"
		startup-script = "echo METADATA > /var/lib/start.txt"
		shutdown-script = "echo METADATA > /var/lib/stop.txt"
	}