* Add details to tracing spans when creating index.
* Log reason for building index.
* Log reason for building index.
* Remove initialization of labels to avoid unnecessary metrics.
* Track succcessful, failed and skiped index builds. Track index build time for individual index, not all indexes.
* Revert removal of labels initialization.
* 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