Alerting: Fix dates stored in local time when pausing alerts (#19525)

* Make tests more sensitive to timezone.

* Time stamps should use UTC for consistency.

* Test: Assert state is paused after pauseAllAlerts call.

pkg/services/sqlstore/alert_test.go

@@ -12,7 +12,8 @@ import (
 func mockTimeNow() {
 	var timeSeed int64
 	timeNow = func() time.Time {
-		fakeNow := time.Unix(timeSeed, 0)
+		loc := time.FixedZone("MockZoneUTC-5", -5*60*60)
+		fakeNow := time.Unix(timeSeed, 0).In(loc)
 		timeSeed++
 		return fakeNow
 	}
@@ -84,6 +85,12 @@ func TestAlertingDataAccess(t *testing.T) {
 					So(err, ShouldNotBeNil)
 				})
 
+				Convey("alert is paused", func() {
+					alert, _ = getAlertById(1)
+					currentState := alert.State
+					So(currentState, ShouldEqual, "paused")
+				})
+
 				Convey("pausing alerts should update their NewStateDate", func() {
 					alert, _ = getAlertById(1)
 					stateDateAfterPause := alert.NewStateDate