Fix unstable test TestBroadcastEventHandlers

[adamdickmeiss]

TestBroadcastEventHandlers (2.06s)
eventbus_test.go:184: Expected to have some events
eventbus_test.go:190:
Error Trace: /home/adam/proj/crosslink/broker/test/events/eventbus_test.go:190
Error: Not equal:
expected: 8
actual : 7
Test: TestBroadcastEventHandlers
Messages: Total number of events should match the number of created tasks
eventbus_test.go:194: Request event 0: 872b2beb-78dd-4cad-8132-747ee5340d53
eventbus_test.go:194: Request event 1: cf09ec08-9dd1-435e-b990-012e36477a5c
eventbus_test.go:198: Received event 0 from pool 0: 872b2beb-78dd-4cad-8132-747ee5340d53
eventbus_test.go:198: Received event 0 from pool 1: cf09ec08-9dd1-435e-b990-012e36477a5c
eventbus_test.go:198: Received event 1 from pool 1: 872b2beb-78dd-4cad-8132-747ee5340d53
eventbus_test.go:198: Received event 0 from pool 2: cf09ec08-9dd1-435e-b990-012e36477a5c
eventbus_test.go:198: Received event 1 from pool 2: 872b2beb-78dd-4cad-8132-747ee5340d53

Fix by lock the append of events received as it can happen async.

[Copilot]

Pull request overview

This PR aims to stabilize the TestBroadcastEventHandlers integration test by preventing concurrent unsynchronized access to shared slices that collect received events.

Changes:

• Introduces a sync.Mutex to guard concurrent append operations into receivedAr and requestReceived1.
• Adds locking around reads of those slices during predicate polling and failure logging.
• Fixes the failure-path condition in TestBroadcastEventHandlers to compare against the correct expected total (noEvents*(noPools+1)).