Revert "grpc: call balancer.Close() before returning from ccBalancerWrapper.close()" (#4391)
Revert "grpc: call balancer.Close() before returning from ccBalancerWrapper.close()" (#4391)

This reverts commit 28078834f35b944281662807d8ec071645c37307.
menghanl/grpc-go,stanley-cheung/grpc-go,grpc/grpc-go,grpc/grpc-go,menghanl/grpc-go,dfawley/grpc-go,dfawley/grpc-go,stanley-cheung/grpc-go