test: remove tests for CollectionServiceImpl class

The following issue won't be fixed:
Closes #1194
Closes #1614

Part of #1668

Author: php-coder

src/main/java/ru/mystamps/web/feature/collection/CollectionServiceImpl.java

@@ -131,7 +131,6 @@ public boolean isSeriesInCollection(Integer userId, Integer seriesId) {
 		return collectionDao.isSeriesInUserCollection(userId, seriesId);
 	}
 
-	// @todo #1123 CollectionService.findSeriesInstances(): add unit tests
 	@Override
 	@Transactional(readOnly = true)
 	@PreAuthorize(HasAuthority.UPDATE_COLLECTION)
@@ -208,7 +207,6 @@ public CollectionInfoDto findBySlug(String slug) {
 		return collectionDao.findCollectionInfoBySlug(slug);
 	}
 
-	// @todo #1605 CollectionService.findAllForSitemap(): add unit tests
 	@Override
 	@Transactional(readOnly = true)
 	public List<SitemapInfoDto> findAllForSitemap() {