DSpace 7: Missing delete button for non-repeatable field with value pairs

[f-rapp]

Description
Missing delete button for non-repeatable field with value pairs

To reproduce
Select a value for a non-repeatable field with value pairs. E.g. Language "English".
Try to delete the value and go back to no entry.

Expected behavior
There should be a delete button to empty the field.
or:
There should be an emtpy entry in the dropdown that you can fall back to. Please note: If there is an empty value included in the value-pairs already, that's not a solution. This empty value is not displayed properly, and if selected, it says "undefined".

Related work
#2568

[tdonohue]

Closing as this is the same issue as #2568. So, it's a duplicate. The only difference in these fields is that one is repeatable. The core bug is that the value cannot be removed or cleared...so the same fix will solve both tickets.