[Bug]: REST Client - breaking change with proxy settings and REST Connection

### Apache Hop version?

2.19

### Java version?

ZuluJDK 21

### Operating system

Linux

### What happened?

In Hop 2.19 the **REST Connection** metadata now includes settings for using a proxy to connect.

When using a "proxied" connection in a **REST Client**, the proxy settings in it are now disabled. If specified in a previous version of Hop, they are also ignored and need to be specified/moved in the selected connection.

_(yep, this is an auto-resolved bug... feel free to discard or use it to update any relevant documentation 😅)_

### Issue Priority

Priority: 3

### Issue Component

Component: Transforms

Start by comparing the REST Connection proxy settings with the REST Client behavior described for Hop 2.19. Then inspect the relevant REST Client and REST Connection documentation and update it to explain where proxy settings now belong and how previous configurations are affected. Done means the current behavior and migration guidance are clear.

Written by the indexing model from the issue text.