Fix replace-rncore-version to extract tarball via temp dir for EdenFS compatibility

Extract the rncore tarball to a temporary directory on a regular filesystem
first, then move it to the final location. This avoids issues with partial
tar extraction on EdenFS where extracting directly can silently produce
incomplete results. Also adds extraction verification and mv/cp fallback logic.

## Changelog:
[Internal] - Fix rncore tarball extraction on EdenFS by extracting to a temp dir first and moving to final location