feat: PC-12940/PC-12941 Allow to configure budget drop condition type

[nobl9-adam-szymanski]

Motivation

Allow to configure new condition type based on budget drop.

Summary

1. Extend set of alerting conditions with new measurement budgetDrop.
2. Block possibility to set lastsFor for new condition type.
3. Force to set alertingWindow for new condition type.
4. Operator is GTE.

Testing

Run sloctl apply -f fast-budget.yaml:

apiVersion: n9/v1alpha
kind: AlertPolicy
metadata:
 name: fast-budget-drop
 displayName: Fast budget drop (5% over the last 1h)
spec:
 description: The error budget dropped by 5% of the error budget based on the 1h observation window
 severity: High
 coolDown: "5m"
 conditions:
   - measurement: budgetDrop
     value: 0.05
     alertingWindow: 1h
     op: gte

Release Notes

Add support for new alerting condition based on budget drop with new measurement budgetDrop.

Example:

apiVersion: n9/v1alpha
kind: AlertPolicy
metadata:
 name: fast-budget-drop
 displayName: Fast budget drop (5% over the last 15m)
spec:
 description: The error budget dropped by 5% of the error budget based on the 15m alerting window
 severity: High
 coolDown: "5m"
 conditions:
   - measurement: budgetDrop
     value: 0.05
     alertingWindow: 15m
     op: gte