[Serverless][8.17][8.16]: Security – Alerts section bugs

[nastasha-solomon]

Fixes #6038

Serverless:

• Manage detection alerts
  • View and filter detection alerts: Updates the second bullet and makes the explanation more generic.
  • Customize the Alerts table: Fixes the incorrect field name for the Sort fields x option.
• Reduce notifications and alerts: Fixed the links to the maintenance docs and notification docs. Now, they correctly point to Serverless pages.
• View detection alert details | About: Removes the docs for the Last Alert Status Change and MITRE ATT&CK fields and updates the screenshot

ESS: (Same changes as above)

• Manage detection alerts
  • View and filter detection alerts
  • Customize the Alerts table
• View detection alert details | About

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[natasha-moore-elastic]

Looks great, thanks for fixing these!