Flake test: `TestWorkerPoolQueueWorkerIdleReset`

[silverwind]

Seen here:

--- FAIL: TestWorkerPoolQueueWorkerIdleReset (0.51s)
    workerqueue_test.go:270: 
          Error Trace:  /home/runner/work/gitea/gitea/modules/queue/workerqueue_test.go:270
          Error:        Not equal: 
                        expected: int(2)
                        actual  : int32(3)
          Test:         TestWorkerPoolQueueWorkerIdleReset
FAIL

[wxiaoguang]

-> Fix queue test #30646