* fix(ci): point OSS contributor workflows to litellm_oss_staging
Workflow triggers and guard error messages incorrectly referenced litellm_oss_branch; update them to the branch we actually use for external contributions.
* fix(ci): include test-rust.yml in litellm_oss_staging rename
Missed test-rust.yml when updating OSS contributor target branch references.
Co-authored-by: Cursor <cursoragent@cursor.com>
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Co-authored-by: Cursor <cursoragent@cursor.com>
Adds a GHA that fails PRs to main unless the head branch is
'litellm_internal_staging' or 'litellm_hotfix_*'. Also fails merge_group
events since merge queue is not in use.
