The path to save found search results to annotations is reset on the annotations table removing

Scenario to reproduce:

1. Open "data/samples/Genbank/murine.gb".
2. Open "Search in Sequence" options panel tab.
3. Expand "Save annotation(s) to" options group.
   Expected state: there is a default new document path.
4. Select "New document" option to save annotations to.
5. Set any non-default path.
6. Remove the annotations table object from the project.
   Expected state: the widget on the options panel has been updated (existing document combobox is cleared), the custom path has not been removed.
   Current state: the widget on the options panel has been updated, the custom path is reset to the default value.