[Backport] StaticDropdown field disappears from the document

Description:
The static dropdown disappears from the Document when we are clicking on "Choose one value".

Steps to Reproduce:

1.  Create a new document type with one column
2.  Add Static Dropdown field
3.  Add at least 2 options
4.  Make Static Dropdown an optional field
5.  Commit Document type
6.  Create a new Document using this document type
7. Try to choose any option from the dropdown and then click on the "Choose one value" option

As a result, the dropdown will disappear from the document.

Client reported this issue on 14.7.5 but was able to reproduce the same issue on 15.1.0 too.