Do not show already selected items in filter search

[HLeithner]

Is your feature request related to a problem? Please describe.
If you search for an item it also shows the already added items.

Describe the solution you'd like
Didn't found an option to disable this behaviour

Describe alternatives you've considered
None.

Additional context
Relevant to #1352 since if you add multiple you would like to have it filtered and click only which are not added already

[samuelhwilliams]

yeah both of these are definitely how I expected it to work out of the box, so would love to see these come in

I think this is a dupe of #1313