[Bug] Exceptions does not apply to new events

[admiralbenbou]

Describe the bug
Exceptions are not applied to new events and alerts are generated. At the same time, alerts are closed manually by saving the exception unchanged with the checkbox "Close all alerts that match this exception and were generated by this rule"

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Security\Detect\Exceptions'
2. Click on 'Net command via SYSTEM account'
3. Click on 'Exceptions'
4. Click on 'Add new Exception'
5. Field - process.parent.command_line, operator - is , value - 'some value', in our case it may be '"C:\WINDOWS\system32\cmd.exe" /c whoami /all | findstr /I /C:"S-1-5-32-544"'
6. Press 'Save'
7. Run this command on the host with elastic agent
8. See an alert in Security\Detect\Alerts
9. Go to 'Security\Detect\Exceptions'
10. Click on 'Exceptions'
11. Click on 'Edit' in our exception added in p.4
12. Switch checkbox "Close all alerts that match this exception and were generated by this rule" and click 'Save'
13. See that alert from p.8 is closed now
14. That also works for duplicates of built-in rules - 'Net command via SYSTEM account [Duplicate]'

Expected behavior
Alert from p.8 is not generated

Screenshots

Desktop (please complete the following information):

• OS:
• Version:

Additional context
Kibana v 7.16.3

[elasticmachine]

Pinging @elastic/security-solution (Team: SecuritySolution)