onedrive: fix "The upload session was not found" errors

Before this change, sometimes, perhaps on heavily loaded sharepoint
servers, uploads would sometimes fail with the error:

{"error":{"code":"itemNotFound","message":"The upload session was not found"}}

This retries the upload after a 5 second delay up to --low-level-retries times.

Fixes #8545

backend/onedrive/onedrive.go

@@ -2469,6 +2469,10 @@ func (o *Object) uploadFragment(ctx context.Context, url string, start int64, to
 				return false, nil
 			}
 			return true, fmt.Errorf("retry this chunk skipping %d bytes: %w", skip, err)
+		} else if err != nil && resp != nil && resp.StatusCode == http.StatusNotFound {
+			fs.Debugf(o, "Received 404 error: assuming eventual consistency problem with session - retrying chunk: %v", err)
+			time.Sleep(5 * time.Second) // a little delay to help things along
+			return true, err
 		}
 		if err != nil {
 			return shouldRetry(ctx, resp, err)