We should not take the number of files in an `UpdateIndexStoreTaskDescription` as an indication on how important the task is. If we do need this functionality, eg. because we want to update the index of files with syntactic matches for a rename term, this should be communicated using a specific purpose similar to `TargetPreparationPurpose`. Since the only reason we update the index store for a file right now is background indexing, such a check is not needed.