Provider 4xx on an instance-name lookup is rarely actionable -- it
usually reflects a configuration state (deleted org, revoked token)
rather than a system error worth paging on. Downgrade Probo's own
log entry to Warn. The kit/worker entry for the same failure is
still Error pending the retry-limit work, which will mark sources
synced after N attempts and stop the duplicate log line.
Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>