refactor: Address synchronization and buffered channels

[casibbald]

• Added mutex synchronization and buffered channels to fix race conditions
• Added WaitGroup to ensure goroutine completion in concurrent test

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Release notes

Documentation Changes

[Copilot]

Pull Request Overview

This PR addresses race conditions in concurrent test code by adding proper synchronization mechanisms. The changes focus on fixing test reliability issues that could occur when multiple goroutines access shared resources simultaneously.

• Added mutex synchronization to prevent concurrent resource updates in simulateReconcile
• Converted unbuffered channel to buffered and improved goroutine cleanup patterns
• Added WaitGroup to ensure proper goroutine completion in concurrent test scenarios

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
core/server/sync_test.go	Added mutex parameter to simulateReconcile calls and converted to buffered channel with improved error handling pattern
core/clustersmngr/factory_caches_test.go	Wrapped concurrent goroutines with WaitGroup to ensure completion before assertions

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[casibbald]

@erikgb Moved it here, it might have been a red herring. lets keep this PR open and monitor other builds