Backport of keyring: E2E testing for KMS/rotation into release/1.8.x

[hc-github-team-nomad-core]

Backport

This PR is auto-generated from #23601 to be assessed for backporting due to the inclusion of the label backport/1.8.x.

The below text is copied from the body of the original PR.

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In #23580 we're implementing support for encrypting Nomad's key material with external KMS providers or Vault Transit. In #23577 we're implementing support for prepublishing keys. This changeset updates the E2E infrastructure to use an external KMS and adds tests for rotation.

Ref: https://hashicorp.atlassian.net/browse/NET-10398
Ref: https://hashicorp.atlassian.net/browse/NET-10280
Ref: https://hashicorp.atlassian.net/browse/NET-10334
Ref: #14852
Ref: #23580

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Note to reviewers: this PR requires #23580 and #23577 to be merged before we can merge this. Test run against a build that includes both PRs:

$ go test -v -count=1 ./keyring
=== RUN   TestKeyringRotation
--- PASS: TestKeyringRotation (0.62s)
PASS
ok      github.com/hashicorp/nomad/e2e/keyring  0.632s

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Overview of commits

• a29f9b6