Issue #2280861 by roderik, pcambra: CommentStatistics service followup.

core/modules/comment/comment.install

core/modules/comment/src/CommentStatistics.php

core/modules/comment/src/CommentStatisticsInterface.php

core/modules/comment/src/CommentStorage.php

core/modules/comment/src/CommentStorageInterface.php

core/modules/comment/src/Entity/Comment.php

core/modules/comment/tests/src/Entity/CommentLockTest.php

core/modules/tracker/tracker.pages.inc