[➕ Feature]: Modify the count to only sum **firing** alerts per preset, giving a clearer view of active alerts

[DolevNe]

Is your feature request related to a problem? Please describe.
Keep’s left sidebar shows presets with a number indicating the total alerts in each. Currently, this number includes all alerts, even those not firing, which can be misleading when assessing active issues.

Describe the solution you'd like
Modify the count to only sum firing alerts per preset, giving a clearer view of active incidents.

Describe alternatives you've considered

• Displaying both total and firing alert counts.
• Adding a toggle to switch between counting all alerts or only firing ones.
• Using color indicators to differentiate active and resolved alerts.

Additional context
This change ensures the sidebar provides a more accurate snapshot of ongoing issues, improving situational awareness.