OZG-7473 improve tests

Based on CR comment.

alfa-client/libs/admin/aggregation-mapping/src/lib/aggregation-mapping-list-container/aggregation-mapping-list/aggregation-mapping-list.component.spec.ts

@@ -50,7 +50,7 @@ describe('AggregationMappingListComponent', () => {
       expect(component.aggregationMappings).toEqual([]);
     });
 
-    describe('_update', () => {
+    describe('update', () => {
       it('should set list state resource', () => {
         component.aggregationMappingListStateResource = aggregationMappingListStateResource;
 
@@ -99,18 +99,16 @@ describe('AggregationMappingListComponent', () => {
       fixture.detectChanges();
     });
 
+    it('should have list', () => {
+      expectComponentExistsInTemplate(fixture, ListComponent);
+    });
+
     it('should have spinner with state resource', () => {
-      expectComponentExistsInTemplate(fixture, SpinnerComponent);
       const comp = getElementFromFixtureByType(fixture, SpinnerComponent);
       expect(comp.stateResource).toEqual(aggregationMappingListStateResource);
     });
 
-    it('should have list', () => {
-      expectComponentExistsInTemplate(fixture, ListComponent);
-    });
-
     it('should have list item with mapping', () => {
-      expectComponentExistsInTemplate(fixture, AggregationMappingListItemComponent);
       const comp = getElementFromFixtureByType(fixture, AggregationMappingListItemComponent);
       expect(comp.aggregationMapping).toEqual(
         getEmbeddedResources(aggregationMappingListStateResource, AggregationMappingListLinkRel.LIST)[0],