Bug report
TimePicker filter does not show all time slots after clearing the filter since v. 2020.3.1021

Reproduction of the problem
Dojo: https://dojo.telerik.com/oseJEqay
1. Open the filter menu and select a time period to filter, Apply filter.
2. Open the filter menu again, open the drop-down you can see all items.
3. Click clear filter.
4. Open the filter menu again, click on the drop-down, you can see that the only item on that list for time picker is 12am.


### Expected/desired behavior
All time slots shall be present in the dropdown list