[Lens] Fix broken test (#70117) (#70148)

Co-authored-by: Wylie Conlon <william.conlon@elastic.co>

Author: mbondyra

x-pack/plugins/lens/public/indexpattern_datasource/loader.test.ts

@@ -318,7 +318,6 @@ describe('loader', () => {
           a: sampleIndexPatterns.a,
         },
         layers: {},
-        showEmptyFields: false,
       });
       expect(storage.set).toHaveBeenCalledWith('lens-settings', {
         indexPatternId: 'a',
@@ -341,7 +340,6 @@ describe('loader', () => {
           b: sampleIndexPatterns.b,
         },
         layers: {},
-        showEmptyFields: false,
       });
     });