### What problem does this PR solve?
`common/misc_utils.once` set `executed=True` before invoking the wrapped
function, so an exception on the first call permanently disabled future
calls and returned the cached `None`.
This change marks `executed=True` only after a successful call, allowing
retries after transient failures while preserving once-only behavior
after success. It also adds regression tests for retry-after-exception
and thread-safe single execution.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
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Co-authored-by: Harsh Kashyap <harshkashyap@Harshs-MacBook-Pro.local>
Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: Jin Hai <haijin.chn@gmail.com>