ECMS-6193: Advanced search: Impossible to search with date constraints

Problem analysis:
- ECMS-5904 escapes "less than" and "greater than" characters in date constraints because these marks are also used in XSS scripts.
  These escaped values are then stored in DB. It is therefore impossible to execute search query with date constraints.

Fix description:
- Revert ECMS-5904 and escape XSS characters in gtmpl file when rendering the form.