MM-61947 Run DND expiry job more often and round expiry time to match interval (#29938)

* MM-61947 Run DND expiry job more often and round expiry time to match interval

* Move comment to make it godoc-compatible

* Change truncateDNDEndTime to work with seconds

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/public/model/status.go

@@ -5,6 +5,7 @@ package model
 
 import (
 	"encoding/json"
+	"time"
 )
 
 const (
@@ -16,6 +17,9 @@ const (
 	StatusCacheSize      = SessionCacheSize
 	StatusChannelTimeout = 20000  // 20 seconds
 	StatusMinUpdateTime  = 120000 // 2 minutes
+
+	// DNDExpiryInterval is how often the job to expire temporary DND statuses runs.
+	DNDExpiryInterval = 1 * time.Minute
 )
 
 type Status struct {
@@ -24,8 +28,12 @@ type Status struct {
 	Manual         bool   `json:"manual"`
 	LastActivityAt int64  `json:"last_activity_at"`
 	ActiveChannel  string `json:"active_channel,omitempty" db:"-"`
-	DNDEndTime     int64  `json:"dnd_end_time"`
-	PrevStatus     string `json:"-"`
+
+	// DNDEndTime is the time that the user's DND status will expire. Unlike other timestamps in Mattermost, this value
+	// is in seconds instead of milliseconds.
+	DNDEndTime int64 `json:"dnd_end_time"`
+
+	PrevStatus string `json:"-"`
 }
 
 func (s *Status) ToJSON() ([]byte, error) {