[Backport release/0.0.14] docs(teleop): correct broker key and identity guidance

[github-actions]

Description

Backport of #4087 to release/0.0.14.

[greptile-apps]

Confidence Score: 5/5

Safe to merge: the updated environment and documentation match the broker's implemented defaults and optional identity behavior.

What we checked:

• Ran the offline configuration verifier against the parent and current environment templates using the real hosted blueprint parser and broker configuration constructor.
• The parent environment overrides the broker URL and robot ID, while the current environment leaves both unset, resolving to https://api.dimensional.org and robot_id=None.
• Ran the focused broker credential and optional-identity test successfully (1 passed).
• The verifier source used for this validation is included with the captured outputs.
• For deeper validation, runtime/default and identity contract results were captured in after logs and before/after comparisons, the existing focused identity test shows 1 passed, and the verifier script hosted-broker-config-contract.py was executed.

Summary

• Removes obsolete hosted teleoperation environment overrides so the supported broker endpoint and API-key-derived robot identity apply by default.
• Updates API-key format and creation guidance across runtime messages, integration guidance, and hosted teleoperation documentation.
• The configuration path was exercised with the real blueprint parser and broker configuration construction; no issues were found.

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