Remove the Parent select field from vertical sortable lists and add it to vertical and horizontal sortable lists

I was not sure which component would be appropriate in this case since the issue touches several different modules. Menus are for example apply to the system module while manage form display pages apply to the field ui module. But there might be more different cases. Apologies.

The parent field is useful when you have a module like field_group that can add a fieldset or something where items can be nested into. Then the parent field does not display unhelpful values.

When field_group is not enabled it does seem unnecessary I agree, the values shown in the select do not seem correct, Content and Disabled are for the region select, not the parent select.

The manage form display (and the other manage display, block placement) are actually hierarchical interfaces with the region being a parent of the rows. I mean technically it makes sense and I agree it's not the user see, just providing some context here.

oh that aspect i haven't considered for vertically ordered lists. it looked like that the order options were sort of interchanged between vertical and hierarchic sortable lists.

i wondered would it make sense instead of removing the parent column from pages with vertically ordered list as currently suggested in the proposed resolution instead make the display conditional? meaning in cases like a fresh install of Core only hide that parent column and in cases like a contrib module like field_group installed show it?

We have 2 taxonomy terms with the same name for JavaScript on d.o with different tids, sometimes they get changed automatically depending on which one is used in the autocomplete. it happens.

I'm not sure about adding the parents column conditionally, it sounds like it'll be a headache for backwards compatibility, i'm pretty sure it's not just field_group that make use of this.