Configuration patching not working in Identity Server

I am working on a Sitecore Managed Cloud project and for that, I want to patch AllowedCorsOrigins node to add AllowedCorsOriginsGroup2 for adding custom domain of CM site in Identity Server.

Since this is a Sitecore Host application so patching should work as explained here.

When I update file (root)\Config\production\Sitecore.IdentityServer.Host.xml directly then everything is working fine as explained here but patching is not.

To patch that file I tried following -

I created a patch file as shown below

<?xml version="1.0" encoding="utf-8" ?><Settings><Sitecore><IdentityServer>      <Clients><DefaultClient><AllowedCorsOrigins><AllowedCorsOriginsGroup2>https://cm.mysite.com</AllowedCorsOriginsGroup2></AllowedCorsOrigins></DefaultClient></Clients></IdentityServer></Sitecore></Settings>

and kept it in this location - sitecoreruntime>production>Sitecore.IdentityServer.Host.xml

but it's not working. I also tried keeping patch file to sitecoreruntime>config>production>Sitecore.IdentityServer.Host.xml

Tried renaming patch file too to z.Sitecore.IdentityServer.Host.xml but no luck.

After every change, I restarted app service.

Sitecore version - 9.1.1

What am I doing wrong? Is there any way to view the final/merged configuration of Sitecore Host application something similar to showconfig.aspx?