[RETROACTIVE][RBXHDS] Random HTTP 503 responses errors

Between 10:25 UTC and 20:25 UTC, some applications hosted on the OVH RBXHDS zone may have experienced random 503 response errors due to faulty reverse proxies. The issue has been found and is now resolved.

Additional investigations will be conducted to understand why our monitoring system did not report the issue earlier. Apologies for the inconvenience.