Depublishing some app layer methods (#29559)

* Depublishing some app layer methods

* Fixing errors

* Addressing PR review comment

* Using goimports formatting now

server/channels/app/file.go

@@ -399,8 +399,10 @@ func (a *App) findTeamIdForFilename(rctx request.CTX, post *model.Post, id, file
 	return ""
 }
 
-var fileMigrationLock sync.Mutex
-var oldFilenameMatchExp = regexp.MustCompile(`^\/([a-z\d]{26})\/([a-z\d]{26})\/([a-z\d]{26})\/([^\/]+)$`)
+var (
+	fileMigrationLock   sync.Mutex
+	oldFilenameMatchExp = regexp.MustCompile(`^\/([a-z\d]{26})\/([a-z\d]{26})\/([a-z\d]{26})\/([^\/]+)$`)
+)
 
 // Parse the path from the Filename of the form /{channelID}/{userID}/{uid}/{nameWithExtension}
 func parseOldFilenames(rctx request.CTX, filenames []string, channelID, userID string) [][]string {
@@ -1397,7 +1399,6 @@ func populateZipfile(w *zip.Writer, fileDatas []model.FileData) error {
 			Method:   zip.Deflate,
 			Modified: time.Now(),
 		})
-
 		if err != nil {
 			return err
 		}