Failed to convert `time_interval` settings from Prometheus AlertmanagerConfig

[johnnybee78716]

The CR conversion of time_interval definition seems to be missing in ConvertAlertmanagerConfig function.

Sample original config:

apiVersion: monitoring.coreos.com/v1alpha1
kind: AlertmanagerConfig
metadata:
  name: alertmanager-config
spec:
  muteTimeIntervals:
    - name: holidays
      timeIntervals:
        - weekdays:
            - saturday
            - sunday
  receivers:
    - name: default-receiver
  route:
    matchers:
      - matchType: '='
        name: namespace
        value: monitor
    muteTimeIntervals:
      - holidays
    receiver: default-receiver

Expected conversion result:

apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAlertmanagerConfig
metadata:
  name: alertmanager-config
spec:
  time_intervals:
    - name: holidays
      time_intervals:
        - weekdays:
            - saturday
            - sunday
  receivers:
    - name: default-receiver
  route:
    matchers:
      - namespace="monitor"
    mute_time_intervals
      - holidays
    receiver: default-receiver

Actual result:

apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAlertmanagerConfig
metadata:
  name: alertmanager-config
spec:
  receivers:
    - name: default-receiver
  route:
    matchers:
      - namespace="monitor"
    receiver: default-receiver

AlertmanagerConfig 'muteTimeInterval' field definition reference:
https://github.com/prometheus-operator/prometheus-operator/blob/4cadbf7736760a0422072494ec265196d9f8db29/example/prometheus-operator-crd/monitoring.coreos.com_alertmanagerconfigs.yaml#L150

[AndrewChubatiuk]

fixed in release 0.68.0