server: avoid allocations related to tracking excessive pings (#2923)
server: avoid allocations related to tracking excessive pings (#2923)


menghanl/grpc-go,stanley-cheung/grpc-go,menghanl/grpc-go,grpc/grpc-go,dfawley/grpc-go,stanley-cheung/grpc-go,grpc/grpc-go,dfawley/grpc-go