MM-16796: reduce plugin job interval to once per day (#11521)

* MM-16796: reduce plugin job interval to once per day

The Jobs infrastructure isn't currently setup for running frequent jobs,
as it spams the Jobs table with useless records. Update the plugin job
interval to run less frequently -- since the cleanup doesn't affect
semantics anyway -- and clean up the previously created entries in the Jobs table.

plugin/scheduler/scheduler.go

@@ -11,6 +11,8 @@ import (
 	"github.com/mattermost/mattermost-server/model"
 )
 
+const pluginsJobInterval = 24 * 60 * 60 * time.Second
+
 type Scheduler struct {
 	App *app.App
 }
@@ -32,7 +34,7 @@ func (scheduler *Scheduler) Enabled(cfg *model.Config) bool {
 }
 
 func (scheduler *Scheduler) NextScheduleTime(cfg *model.Config, now time.Time, pendingJobs bool, lastSuccessfulJob *model.Job) *time.Time {
-	nextTime := time.Now().Add(60 * time.Second)
+	nextTime := time.Now().Add(pluginsJobInterval)
 	return &nextTime
 }