refactor(app/integration): remove unused TcpConn::target_addr() (#3695)

this method is not used by any test code, nor any other internal code.

this commit removes
`linkerd_app_integration::tcp::TcpConn::target_addr()`.

Signed-off-by: katelyn martin <[email protected]>

Author: cratelyn

linkerd/app/integration/src/tcp.rs

@@ -149,10 +149,6 @@ impl TcpServer {
 }
 
 impl TcpConn {
-    pub fn target_addr(&self) -> SocketAddr {
-        self.addr
-    }
-
     pub async fn read(&self) -> Vec<u8> {
         self.try_read()
             .await