People skill search bugfixes

[RandomTannenbaum]

Currently the people-skill search has several bugs:

• When adding the first new row and the default row has no value selected, the dropdown in the default row is automatically set to the first value of the dropdown.
• When selecting the same skill twice no results are found.
• The turboframes we utilize (one for the search filters and one for the results) dont seem to work, since updating the slider for the skill level triggers a page refresh.
• Only relevant if the upgrade to Rails 8 is already merged: The update from Rails 7.1 to 7.2 introduced flaky specs. The fill_out_row method in the spec people_skill_search sometimes fails to update the slider in firefox.
• The styling is a bit off. The newly added rows are not aligned with the default row:

ToDo

• Fix bugs that are described above
• Do a thorough smoke tests and if you find new bugs also fix them