unreliable test: startSecurityScanPerformanceTest

[justinmk3]

https://github.com/aws/aws-toolkit-vscode/actions/runs/10498763649/job/29084326983?pr=5458

  1) startSecurityScanPerformanceTest
       Should calculate cpu and memory usage for file scans:

      AssertionError [ERR_ASSERTION]: Expected total CPU usage for Should calculate cpu and memory usage for file scans to be less than 50. Actual CPU usage was 85.47574143312488
      + expected - actual

      -false
      +true
      
      at assertPerformanceMetrics (d:\a\aws-toolkit-vscode\aws-toolkit-vscode\packages\core\src\shared\performance\performance.ts:100:11)
      at Context.<anonymous> (d:\a\aws-toolkit-vscode\aws-toolkit-vscode\packages\core\src\shared\performance\performance.ts:88:9)

[Hweinstock]

Fixed by #5786