[mob][photos] Only add initialGalleryFilter to filters to avoid in recommendations list when there are no applied filters

This resolves a bug: If 'A' is the initialGalleryFilter and a filter 'B' is applied (in this state both A and B filters are applied), and then the filter 'A' is removed, in recommendations, filter 'A' is not recommended since it's passed as a filter to avoid in recommendations

mobile/lib/ui/viewer/gallery/state/search_filter_data_provider.dart

@@ -98,13 +98,18 @@ class SearchFilterDataProvider {
 
     filters.sort((a, b) => b.relevance().compareTo(a.relevance()));
 
+    final List<HierarchicalSearchFilter> filtersToAvoid = [
+      ...appliedFilters,
+      ...recommendations,
+    ];
+
+    if (appliedFilters.isEmpty) {
+      filtersToAvoid.add(initialGalleryFilter);
+    }
+
     _recommendedFiltersNotifier.addFilters(
       filters,
-      filtersToAvoid: [
-        initialGalleryFilter,
-        ...appliedFilters,
-        ...recommendations,
-      ],
+      filtersToAvoid: filtersToAvoid,
     );
   }
 }