Revert " channelz: stage 4 - add security and socket option info" (#2124)

Reverts grpc/grpc-go#2098

Appengine will fail with the error below:
```
go-app-builder: Failed parsing input: parser: bad import "syscall" in google.golang.org/grpc/channelz/funcs.go from GOPATH
```

The root cause of it is in type_linux.go.
629f6bc5e5/channelz/types_linux.go (L21-L25)

server.go

@@ -481,8 +481,7 @@ type listenSocket struct {
 
 func (l *listenSocket) ChannelzMetric() *channelz.SocketInternalMetric {
 	return &channelz.SocketInternalMetric{
-		SocketOptions: channelz.GetSocketOption(l.Listener),
-		LocalAddr:     l.Listener.Addr(),
+		LocalAddr: l.Listener.Addr(),
 	}
 }