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/store/store.go

@@ -703,7 +703,7 @@ type FileInfoStore interface {
 	SetContent(fileID, content string) error
 	Search(paramsList []*model.SearchParams, userID, teamID string, page, perPage int) (*model.FileInfoList, error)
 	CountAll() (int64, error)
-	GetFilesBatchForIndexing(startTime int64, startFileID string, limit int) ([]*model.FileForIndexing, error)
+	GetFilesBatchForIndexing(startTime int64, startFileID string, includeDeleted bool, limit int) ([]*model.FileForIndexing, error)
 	ClearCaches()
 	GetStorageUsage(allowFromCache, includeDeleted bool) (int64, error)
 	// GetUptoNSizeFileTime returns the CreateAt time of the last accessible file with a running-total size upto n bytes.