To configure the proxy to redirect the PAC files from the browser "Automatic Configuration Script", is not possible per the technical limitation with the browser.
On the browser, configuring the "Automatic Configuration Script", and the "Proxy Server" to use the production proxies will not achieve this. The "Automatic Configuration Script" will override the "Manual Proxy Settings", and the browser will only use the "Proxy Server" once it fails the automatic configuration script. Once the proxy server is used, the browser will send the client request (e.g.: www.google.com) to the proxy, instead of getting the PAC file for automatic configuration script.
URL redirect/forwarding is not suitable in achieving this objective and cannot work per the description mentioned above. For updating new "Automatic Configuration Script" settings, we suggest using Microsoft Group Policy Object (GPO) in achieving the desire outcome.