d7_metatag_field_instance_widget_settings show wrong records count

Problem/Motivation

When Metatag is used on a migrate_upgrade project to migrate from D7, the field_instance_widget_settings shows the wrong record count after the fact, e.g.:

  Import from       upgrade_d7_metatag_field_instan   Idle        1       8          -7            2021-02-28 10:59:58  
  Drupal 7          ce_widget_settings_node_page                                                                        
  (migrate_drupal                                                                                                       
  _7)                                                                                                                   

This shows 1 source record but 8 records actually migrated.

Proposed resolution

Fix the logic.
Fix the tests.

Remaining tasks

Fix the logic.
Fix the tests.

User interface changes

n/a

API changes

n/a

Data model changes

n/a