[1.21.11] feat: replace BlockListChecker with allow-all implementation

[link762698]

Type of change

• Bug fix
• New feature

Description

Backport of #6517 by @Big-Iron-Cheems for 1.21.11.

This PR disables the blocklist provided by MojangBlockListSupplier via https://sessionserver.mojang.com/blockedservers.
In 1.21.11, the AddressCheck class used on master is mapped as BlockListChecker; the behavior remains the same.
This effectively lets users connect to any blocked server.

Related issues

#6517

How Has This Been Tested?

• gradlew.bat clean build with JDK 21.0.11.
• runClient initialized without Mixin target, injection, or application errors.
• Tested in production with Minecraft 1.21.11 and Fabric Loader 0.18.4.
• Tested via successful connection to play.6b6t.org and a normal server.

Checklist:

• My code follows the style guidelines of this project.
• I have added comments to my code in more complex areas.
• I have tested the code in both development and production environments.

[Big-Iron-Cheems]

Made a proper cherry pick for 1.21.11, committed as 6e5d691.