MM-53747: Create job to encode older image paths (#24073)

Bifrost now encodes all image paths. Due to this
one-way translation, we need to encode all the older
image paths as well.

After this is done, we can remove the double-lookup.

https://mattermost.atlassian.net/browse/MM-53747

```release-note
NONE
```

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

server/channels/app/server.go

@@ -54,6 +54,7 @@ import (
 	"github.com/mattermost/mattermost/server/v8/channels/jobs/post_persistent_notifications"
 	"github.com/mattermost/mattermost/server/v8/channels/jobs/product_notices"
 	"github.com/mattermost/mattermost/server/v8/channels/jobs/resend_invitation_email"
+	"github.com/mattermost/mattermost/server/v8/channels/jobs/s3_path_migration"
 	"github.com/mattermost/mattermost/server/v8/channels/product"
 	"github.com/mattermost/mattermost/server/v8/channels/store"
 	"github.com/mattermost/mattermost/server/v8/channels/utils"
@@ -1568,6 +1569,11 @@ func (s *Server) initJobs() {
 		import_delete.MakeScheduler(s.Jobs),
 	)
 
+	s.Jobs.RegisterJobType(
+		model.JobTypeS3PathMigration,
+		s3_path_migration.MakeWorker(s.Jobs, s.Store(), s.FileBackend()),
+		nil)
+
 	s.Jobs.RegisterJobType(
 		model.JobTypeExportDelete,
 		export_delete.MakeWorker(s.Jobs, New(ServerConnector(s.Channels()))),