fix: client and server disconnect warnings

[NoelStephensUnity]

Purpose of this PR

This fix:

• Prevents the warning message from being logged on the client side when shutting down from the client side and the developer log level is set.
• Assures that a server or host does not send itself a disconnect message.
• Separates the transport id clean up between client and host/server upon handling a disconnect event to assure the server/host has access to this transport id when processing a client that disconnected.
• Defers the complete disconnection, server side, to the end of the frame when disconnecting a client with a reason in order to assure the disconnect reason is sent prior to closing the transport connection.

Jira ticket

MTTB-1739

Changelog

• Changed: When a server is disconnecting a client with a reason it now defers the complete transport disconnect sequence until the end of the frame after the server's transport has sent all pending outbound messages.
• Fixed: Issue where a warning message was being logged upon a client disconnecting from a server when the log level is set to developer.
• Fixed: Issue where the server or host would no longer have access to the transport id to client id table when processing a transport level client disconnect event.

Documentation

• No documentation changes or additions were necessary.

Testing & QA (How your changes can be verified during release Playtest)

Functional Testing

Manual testing :

• Manual testing done
  • Issue-1695283-Replication.zip

Replication Project

Validating the Fix

• Open the project.
• Start at least 1 MPPM virtual client.
• Enter play mode.
• Once the client is connected:
  • (for simplicity) Clear both the editor and virtual client logs.
  • Click the Disconnect button on the client side.
    • No warnings should be logged
    • 
  • Click the Shutdown button on the host side.
    • No warnings should be logged
    • 

Replicating the issue

• Switch to an earlier version of NGO (i.e. v2.7.0) via package manager--> add package by name
  • Name: com.unity.netcode.gameobjects
  • Version: 2.7.0
• Repeat the above steps
  • Clicking Disconnect on the client side should generate a warning log on the client and two on the host.
  • 

Automated tests:

• Covered by existing modified automated tests
• Covered by new automated tests
  • VerifyNoWarningOnClientDisconnect

Does the change require QA team to:

• Review automated tests?
• Execute manual tests?
• Provide feedback about the PR?

If any boxes above are checked the QA team will be automatically added as a PR reviewer.

Backports

This is a v2.x only issue.

[EmandM]

🎉

Not needed