services: move channelz proto into normalized directory structure

diff --git a/services/src/generated/main/java/io/grpc/channelz/v1/GetServerSocketsResponse.java b/services/src/generated/main/java/io/grpc/channelz/v1/GetServerSocketsResponse.java
index d675183..39e6647 100644
--- a/services/src/generated/main/java/io/grpc/channelz/v1/GetServerSocketsResponse.java
+++ b/services/src/generated/main/java/io/grpc/channelz/v1/GetServerSocketsResponse.java
@@ -1,5 +1,5 @@
 // Generated by the protocol buffer compiler.  DO NOT EDIT!
-// source: io/grpc/channelz.proto
+// source: grpc/channelz/channelz.proto
 
 package io.grpc.channelz.v1;