remove deprecated resource fields from Allocation struct

[tgross]

As part of the "client v2" effort for Nomad 0.9 we changed how allocated resources were tracked, but we ended up leaving the existing struct fields around. All consumers of these fields have been updated to handle the newer fields for a very long time.

Remove the fields from the nomad/structs package version of the object, and formally deprecate them in the api package. This also requires removing the upgrade path in the client state database, but the state database is automatically updated on agent upgrades and Nomad clients older than 1.6 have been non-functional since 1.9. So this only impacts users trying to restore from pre-0.9 backups of their state stores, which seems safe.

Ref: #28447 (comment)

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[chrisroberts]

I'm familiarizing myself with where these were still in use. All these adjustments look great to me so far. I did find that AllocatedResources.OldTaskResources() still exists but should probably be removed with this changeset.

Outside of that, I think the only other thing of note I've seen is the ent specific usage of TaskResources.

[tgross]

I'm familiarizing myself with where these were still in use. All these adjustments look great to me so far. I did find that AllocatedResources.OldTaskResources() still exists but should probably be removed with this changeset.

done!

Outside of that, I think the only other thing of note I've seen is the ent specific usage of TaskResources.

gah! The quotas feature uses these pretty heavily in particular. I'll open an ENT PR that moves those uses to AllocatedResources before merging this one.

[tgross]

Working branch for the ENT code in https://github.com/hashicorp/nomad-enterprise/pull/4467. I'll pick that up next week.