Unified Storage/Search: Add max count config for indexing (#107255)

* Add max count config for indexing
* Build empty index when max count is exceeded
* Address linting
* Refactor buildIndexes
* Add test for max count threshold
* Update test doc comments
* Refactor TestBuildIndexes_MaxCountThreshold to not use mock framework
* Rename mocks used in TestBuildIndexes_MaxCountThreshold

* Refactor mockResourceIndex

* Test setting of indexing threshold configs

* Tweak comments, log

* Fix logging in buildEmptyIndex

* Export and reuse TestDocumentBuilderSupplier

* Reuse MockResourceIndex

pkg/storage/unified/sql/backend.go

@@ -300,6 +300,8 @@ func (b *backend) GetResourceStats(ctx context.Context, namespace string, minCou
 			}
 			if row.Count > int64(minCount) {
 				res = append(res, row)
+			} else {
+				b.log.Debug("skipping stats for resource with count less than min count", "namespace", row.Namespace, "group", row.Group, "resource", row.Resource, "count", row.Count, "minCount", minCount)
 			}
 		}
 		return err