Package Manager registration events are not triggered when changing registry

Description:

When switching the registry of an already installed package without changing its version, the Unity Package Manager scripting events registeredPackages and registeringPackages are not fired. This causes issues for workflows that rely on these events to detect package updates or changes in dependencies.

Steps to reproduce:

1.  Add the following scope registry to manifest.json:

   {
     "name": "npmjs",
     "url": "https://registry.npmjs.org/",
     "scopes": [
       "com.stansassets"
     ]
   }
   

2.  Add the package com.stansassets.scene-management@0.1.1-preview in the Unity project.
3.  Modify the scoped registry configuration to use OpenUPM instead

   {
     "name": "OpenUPM",
     "url": "https://package.openupm.com",
     "scopes": [
       "com.stansassets"
     ]
   }
   

4. Wait for the resolve operation to be completed

Actual results: 
Observe that the registeredPackages and registeringPackages events are not triggered after switching the registry.

Expected results: 
The registeredPackages and registeringPackages events should trigger when a package's registry changes, even if the package version remains the same.

Note:
The packages are correctly installed from the correct registry, it is just the event that are not triggered.