TOOL-24368 Use grub packages provided by Ubuntu

[prakashsurya]

Context

We used to have a "boot counter" implemented in GRUB, such that we could detect "reboot loops" (e.g. repeated failures to boot) and automatically boot into an alternate root filesystem which we called the "recovery environment". We've since abandoned that feature, and thus, we can migrate back to using Ubuntu's grub package(s).

Additionally, this was sparked due to the sporadic GRUB boot failures we've seen on customer engines. While we don't have any evidence to support our locally modified of GRUB is causing the boot failures, this change eliminates this as a possibility, and gets us back to using the packages built and tested by Ubuntu.

Testing

• git-ab-pre-push -b delphix-platform is here
• Verified grub packages pulled from Ubuntu's mirror in the build above; e.g.

  10:44:54  Get:240 http://linux-package-mirror.delphix.com/develop/dece9540/ubuntu focal-updates/main amd64 grub-common amd64 2.04-1ubuntu26.17 [1872 kB]
  10:44:54  Get:241 http://linux-package-mirror.delphix.com/develop/dece9540/ubuntu focal-updates/main amd64 grub2-common amd64 2.04-1ubuntu26.17 [590 kB]
  10:44:54  Get:242 http://linux-package-mirror.delphix.com/develop/dece9540/ubuntu focal-updates/main amd64 grub-pc-bin amd64 2.04-1ubuntu26.17 [971 kB]
  10:44:54  Get:243 http://linux-package-mirror.delphix.com/develop/dece9540/ubuntu focal/main amd64 grub-gfxpayload-lists amd64 0.7 [3658 B]
  10:44:54  Get:244 http://linux-package-mirror.delphix.com/develop/dece9540/ubuntu focal-updates/main amd64 grub-pc amd64 2.04-1ubuntu26.17 [125 kB]

[prakashsurya]

do we feel comfortable pushing this 6 days before CC or are we better off integrating this as soon as 20.0 opens up?

I can wait for 20.0.. I think that's fine, and makes sense for a largely untested change like this.