Revert ConnectionFactory return type in some methods

Some changes from main snuck into 5.x during a merge. This affects 3
methods in ConnectionFactory that used to return void and returned
ConnectionFactory because of the unexpected merge.

The change is source-compatible but not binary-compatible. It should not
affect many users, but we try to stick to backward compatibility so we
go back to returning void.

References #1810

Author: acogoluegnes

src/main/java/com/rabbitmq/client/ConnectionFactory.java

@@ -1382,9 +1382,8 @@ public Connection newConnection(
    * @deprecated user {@link #netty()} instead
    */
   @Deprecated
-  public ConnectionFactory setNioParams(NioParams nioParams) {
+  public void setNioParams(NioParams nioParams) {
     this.nioParams = nioParams;
-    return this;
   }
 
   /**
@@ -1415,20 +1414,18 @@ public NioParams getNioParams() {
    * @deprecated Use {@link #netty()} instead
    */
   @Deprecated
-  public ConnectionFactory useNio() {
+  public void useNio() {
     this.nio = true;
     this.netty = false;
-    return this;
   }
 
   /**
    * Use blocking IO for communication with the server. With blocking IO, each connection creates
    * its own thread to read data from the server.
    */
-  public ConnectionFactory useBlockingIo() {
+  public void useBlockingIo() {
     this.nio = false;
     this.netty = false;
-    return this;
   }
 
   /**