BibKnowledge: KBD export regression test case fix

• Makes test_kbd_export_as_list() and test_kbd_export_as_json() analogous so that they use the same expected output. This makes sense because the only difference between these two test cases is the output format.
  
  Note that this change fixes a failed BibKnowledge regression test case. The test was failing due to another reason -- the change of the `rg' default paging behaviour -- but for this we have another test case in the WebSearch module, so the paging behaviour will be tackled that way.