[JENKINS-33339] Allow root volumes to be deleted on termination

[medwards]

Fixes JENKINS-33339

[medwards]

Some things for me to do still:

• Get it to pass unit tests (still not sure how to get this to work locally)
• Verify the UI hooks actually work (Its my first time exposing things to the user)
• Run it in a real environment

If you don't merge beforehand I'll ping y'all when I'm done.

[medwards]

I also change setupEphemeralDeviceMapping and setupCustomDeviceMapping to operate on the device mapping list in the launch specification or run instances request. There's now only one method signature and they append to the list rather than wiping it out.

This also means we can support ephemeral and custom device mapping at the same time now. I'm not sure who has this use-case and it seems like a dramatic change so I didn't include it here.

[medwards]

We're using the snapshot of this internally now and it looks good.

[medwards]

OK, just got back from vacation and am happy to report no leaked volumes and our environment is still stable ^^

[johnnyshields]

Looks good to me! @francisu what do you think?

[medwards]

I've rebased the branch as we got hit by JENKINS-38481 and didn't have it in our custom build of ec2-plugin.

[micahlmartin]

In addition to this, is there a way to configure the size of the root volume or am I just missing it?

[medwards]

I didn't include anything for it. I assumed it was fixed, at least by instance type.