Revert "Avoid tiles wrapping with zooming out, see #1741"

This reverts commit a29c68ce4ac5af3876a583d5af76745ec272f82e.
Fix #1829 "Alert for constraint shows instead of alert for required"

- Form Builder inserts children `xf:constraint` elements when there are custom alerts
- `annotate.xpl` migrates existing forms
- test
Fix #1830 "Required validation must win over other constraints"

- prioritize required constraints