fix(FR-2494): fix stale state on edit open and NaN timeWindow when switching presets

- Add key prop to AutoScalingRuleEditorModal so React remounts when
  editingRuleId changes, ensuring useState initializes from the current
  autoScalingRule (fixes conditionMode/selectedMetricSource/selectedPresetId
  staying stale from the previous create-mode open)
- Guard preset timeWindow auto-fill against NaN: always overwrite the
  timeWindow field when switching presets (prevents stale value from
  previous preset), and skip if Number() produces NaN

Author: agatha197