test(sync): replace cleanup retry magic numbers with constants

Agent-Logs-Url: https://github.com/project-zot/zot/sessions/a8131207-64f5-4461-962a-19aab205da7d

Co-authored-by: rchincha <45800463+rchincha@users.noreply.github.com>

pkg/extensions/sync/sync_test.go

@@ -1551,15 +1551,20 @@ func TestDockerImagesAreSkipped(t *testing.T) {
 
 				// trigger config blob upstream error
 				// remove synced image
+				const (
+					maxRemoveRetries = 5
+					removeRetryDelay = 100 * time.Millisecond
+				)
+
 				downstreamImagePath := path.Join(destDir, testImage)
 
-				for retry := 0; retry < 5; retry++ {
+				for retry := 0; retry < maxRemoveRetries; retry++ {
 					err = os.RemoveAll(downstreamImagePath)
 					if err == nil || !errors.Is(err, syscall.ENOTEMPTY) {
 						break
 					}
 
-					time.Sleep(100 * time.Millisecond)
+					time.Sleep(removeRetryDelay)
 				}
 
 				So(err, ShouldBeNil)