docs: remove SPLUNK_AO_ENV_RENAME.md (HYBIM-832)

[fercor-cisco]

Summary

• Removes docs/SPLUNK_AO_ENV_RENAME.md, which is useful for HYBIM-788 but doesn't need to (and shouldn't) live in the splunk-ao repo.

Jira: HYBIM-832

Test plan

• N/A — doc-only removal

[github-actions]

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