Fix AG date range based filters default values (#4354)

# What this PR does

Fix AG date range based filters default values

## Which issue(s) this PR closes


## Checklist

- [ ] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] Added the relevant release notes label (see labels prefixed w/
`release:`). These labels dictate how your PR will
    show up in the autogenerated release notes.

---------

Co-authored-by: Michael Derynck <michael.derynck@grafana.com>

engine/apps/api/views/alert_group.py

@@ -1,9 +1,7 @@
 import typing
-from datetime import timedelta
 
 from django.core.exceptions import ObjectDoesNotExist
 from django.db.models import Count, Max, Q
-from django.utils import timezone
 from django_filters import rest_framework as filters
 from drf_spectacular.utils import extend_schema, inline_serializer
 from rest_framework import mixins, serializers, status, viewsets
@@ -729,14 +727,9 @@ class AlertGroupView(
         Retrieve a list of valid filter options that can be used to filter alert groups
         """
         api_root = "/api/internal/v1/"
+        default_day_range = 30
 
-        now = timezone.now()
-        week_ago = now - timedelta(days=7)
-
-        default_datetime_range = "{}_{}".format(
-            week_ago.strftime(DateRangeFilterMixin.DATE_FORMAT),
-            now.strftime(DateRangeFilterMixin.DATE_FORMAT),
-        )
+        default_datetime_range = f"now-{default_day_range}d_now"
 
         filter_options = [
             {

grafana-plugin/src/pages/incidents/Incidents.tsx

@@ -307,8 +307,6 @@ class _IncidentsPage extends React.Component<IncidentsPageProps, IncidentsPageSt
 
   renderIncidentFilters() {
     const { query, store } = this.props;
-    const defaultStart = moment().subtract(7, 'days');
-    const defaultEnd = moment().add(1, 'days');
     return (
       <div className={cx('filters')}>
         <RemoteFilters
@@ -323,7 +321,7 @@ class _IncidentsPage extends React.Component<IncidentsPageProps, IncidentsPageSt
             team: [],
             status: [IncidentStatus.Firing, IncidentStatus.Acknowledged],
             mine: false,
-            started_at: `${defaultStart.format('YYYY-MM-DDTHH:mm:ss')}_${defaultEnd.format('YYYY-MM-DDTHH:mm:ss')}`,
+            started_at: 'now-30d_now',
           }}
         />
       </div>