refactor: retry file remove/rename when a file is busy and clean up os detection (#38588)

Rename functions "util.Remove" (remove.go) to "util.RemoveWithRetry"
(file_retry.go) and add comments to clarify their behaviors, also add
tests.

Refactor callers: when no concurrent access (cmd cli, migration, app
init, test), use "os.Xxx" directly.

More details are in `modules/util/file_retry.go`

By the way, clean up OS (windows) detection, make FileURLToPath test
always run

services/org/org.go

@@ -89,7 +89,7 @@ func DeleteOrganization(ctx context.Context, org *org_model.Organization, purge
 	//	so just keep error logs of those operations.
 	path := user_model.UserPath(org.Name)
 
-	if err := util.RemoveAll(path); err != nil {
+	if err := util.RemoveAllWithRetry(path); err != nil {
 		return fmt.Errorf("failed to RemoveAll %s: %w", path, err)
 	}