### Steps to reproduce

* Open a manually scheduled WorkPackage

* Open the datepicker

* Begin of the insertionEnsure "Working days only" is off

* End of the insertion Change the Begin of the insertionfinishEnd of the insertion Begin of the deletion dueEnd of the deletion date

* Toggle the "working days only" Begin of the insertiononEnd of the insertion Begin of the deletion checkboxEnd of the deletion


### What is the buggy behavior?

* The due date is kept while start date and duration are changed causing a weird jump which no user will ever understand


<br>

<img class="op-uc-image op-uc-image_inline" src="/api/v3/attachments/398002/content">

### What is the expected behavior?

* Due date should be kept AND either start date or duration should be kept as well

* [This test](https://github.com/opf/openproject/pull/18425/files#diff-35d35056ea950c36ec9d1a346f6fb0fe98becea4e2d35de0a2fb90527e5335ebR384) should ideally be unset as pending after wards. It checks for [Scenario 14](https://community.openproject.org/projects/openproject/work_packages/62599/activity#scenario-14b-switch-to-manual-change-finish-date-and-non-working-days-back-to-automatic-) of #62599


###

### Environment information

**OpenProject version**

_15.5_

**Browser**

* [x] Chrome
* [ ] Firefox
* [ ] Safari
* [ ] Mobile Safari
* [ ] Other (please specify)

**Operating System**

* [ ] Windows
* [x] Mac OS X
* [ ] Mobile iOS
* [ ] Mobile Android
* [ ] Linux (please specify distro)
* [ ] Chrome OS
* [ ] Other (please specify)

**Language**

English