gRPC-Go: Denial of Service (DoS) via crash due to missing `:authority` and `Host` headers in the xDS servers

gRPC-Go is the Go language implementation of gRPC. Prior to 1.82.2 and 1.83.2, servers created with xds.NewGRPCServer() allow internal/transport/http2_server.go to accept an RPC containing neither the :authority header nor the Host header, while RouteAndProcess in internal/xds/server/routing.go assumes that an authority value exists and indexes the empty slice. A remote client that can complete transport connection establishment can trigger an index-out-of-bounds panic that is not recovered by the per-RPC goroutine and terminates the entire server process. In insecure or ordinary TLS deployments the request can be unauthenticated, while strict mTLS or ALTS deployments require valid transport credentials before the malformed RPC can reach the interceptor. This issue is fixed in versions 1.82.2 and 1.83.2.