Backport of cli: operator debug: respect NOMAD_REGION env var into release/1.10.x

[hc-github-team-nomad-core]

Backport

This PR is auto-generated from #25716 to be assessed for backporting due to the inclusion of the label backport/1.10.x.

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

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Fixes #25672 - tl;dr NOMAD_REGION and NOMAD_NAMESPACE are ignored by nomad operator debug

I thought about having Meta.clientConfig() write Meta.region and Meta.namespace, but that felt off, so I opted for a couple of getters that can hopefully be easily discovered if needed for other cases.

Before:

$ NOMAD_REGION=global NOMAD_NAMESPACE=default nomad operator debug
Starting debugger...

Nomad CLI Version: Nomad v1.10.0
BuildDate 2025-04-09T16:40:54Z
Revision e26a2bd2acac2dcdcb623f4d293bac096beef478
           Region:
        Namespace:
          Servers: (1/1) ... etc etc ...

After:

$ NOMAD_REGION=global NOMAD_NAMESPACE=default nomad operator debug
Starting debugger...

Nomad CLI Version: Nomad v1.10.1-dev
BuildDate 2025-04-21T18:49:12Z
Revision c86d63da13145326ae69649fa9c51601dc16914a+CHANGES
           Region: global
        Namespace: default
          Servers: (1/1) ... etc etc ...

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Overview of commits

• c46521a

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