HYBIM-951 rename O11y token environment variables

[pradystar]

Summary

Rename the O11y SDK token environment variables to make their purpose explicit:

• SPLUNK_AO_SF_TOKEN → SPLUNK_AO_O11Y_TOKEN
• SPLUNK_AO_SF_API_TOKEN → SPLUNK_AO_O11Y_API_TOKEN

Why

The previous names exposed internal SF terminology and did not clearly indicate that these tokens configure O11y Cloud authentication. Since the SDK has not been released, the old names are removed without compatibility aliases.

What changed

• Updated O11y deployment detection, configuration, validation, and authentication.
• Updated the Galileo-core configuration bridge.
• Updated tests, README documentation, A2A examples, and ADK references.
• Kept wire authentication unchanged: O11y requests continue using the X-SF-Token
  header.
• Standalone authentication behavior is unchanged.

Additional fixes

A2A

• Updated A2A compatibility tests to reflect that splunk_ao.* attribute duplication is disabled by default while preserving native gen_ai.* attributes.

ADK

• Restored ADK legacy ingestion_hook compatibility with recursive trace completion.
• Added coverage for nested ADK trace completion.

Testing

2130 passed, 4 skipped; ADK 20 passed; live @log smoke test successfully exported to O11y.

[fercor-cisco]

🤖 This review was generated by the Astra agent (claude-opus-4-8). It may contain mistakes.

Verdict: approve — Clean, complete env-var rename with no stray references; two additional fixes (ADK conclude_all override, A2A test isolation) are correct and well-tested.