[1.21.4] Revert Registries to Frozen on Disconnect when a connection is present

[ChampionAsh5357]

Closes #1932

Moves the call to RegistryManager#revertToFrozen to Minecraft#disconnect to handle every case of the vanilla client disconnecting from some server instance. As we don't want to revert the registries until after all potential usecases are handled, the logic is cached before the connection is released and ran at the end of the method. There is no need to include the memory connection check as this is called regardless of the type of channel used, as evidenced by its prior use in ServerLifecycleHooks#handleServerStopped.

The test provided in the issue was used to verify the logic.

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

Last commit published: 2ea2e0c22efea2a89dbaddc0ad20661f8a05a4ae.

PR Publishing

The artifacts published by this PR:

• 📦 net.neoforged:neoforge:21.4.82-beta-pr-1934-fix-i1932
• 📦 net.neoforged:testframework:21.4.82-beta-pr-1934-fix-i1932

Repository Declaration

In order to use the artifacts published by the PR, add the following repository to your buildscript:

repositories {
    maven {
        name 'Maven for PR #1934' // https://github.com/neoforged/NeoForge/pull/1934
        url 'https://prmaven.neoforged.net/NeoForge/pr1934'
        content {
            includeModule('net.neoforged', 'neoforge')
            includeModule('net.neoforged', 'testframework')
        }
    }
}

MDK installation

In order to setup a MDK using the latest PR version, run the following commands in a terminal.
The script works on both *nix and Windows as long as you have the JDK bin folder on the path.
The script will clone the MDK in a folder named NeoForge-pr1934.
On Powershell you will need to remove the -L flag from the curl invocation.

mkdir NeoForge-pr1934
cd NeoForge-pr1934
curl -L https://prmaven.neoforged.net/NeoForge/pr1934/net/neoforged/neoforge/21.4.82-beta-pr-1934-fix-i1932/mdk-pr1934.zip -o mdk.zip
jar xf mdk.zip
rm mdk.zip || del mdk.zip

To test a production environment, you can download the installer from here.

[neoforged-releases]

🚀 This PR has been released as NeoForge version 21.4.85-beta.

[neoforged-automation]

Created backport PR: #1944