Fix #803 (again) ensure the self referencing nodes are removed

[KevinJump]

Last time we where keeping the nodes that matched (as opposed to removing them).

this fix does that, and does it in the loop so we don't have to create a new version of the list once we've done it.

[Copilot]

Pull Request Overview

This PR fixes issue #803 by properly removing self-referencing nodes from the graph structure during topological sorting. The fix prevents nodes from referencing themselves, which was causing issues in the previous implementation.

• Filters out self-references when building the graph edges to prevent circular dependencies
• Removes unnecessary graph cleaning step that was incorrectly filtering nodes
• Pre-allocates result list capacity for better performance

Comments suppressed due to low confidence (1)

uSync.BackOffice/SyncHandlers/SyncHandlerContainerBase.cs:1

• The removed code was filtering to keep only self-referencing edges (x.Node == x.Edge) instead of removing them. This would have passed only circular references to TopologicalSort, which is incorrect behavior that the current fix addresses properly.

using Microsoft.Extensions.Logging;

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