Fixes
- CPU profile of Gloo at scale (5000+ upstreams) indicated that the
generateXDSSnapshotfunction was taking upwards of 5 seconds of CPU on a ~50 second sample. This change optimizes the code by using creating hashes for the XDS snapshot using deterministic proto marshalling and fnv hashing rather than the reflection-basedmitchellh/hashstructurewhich was benchmarked to be several orders of magnitude slower. (#4084)