Remove destination property content_translation_update_definitions from migrations

Problem/Motivation

Revisited this and discovered that the destination property content_translation_update_definitions is no longer used anywhere in core. I used grep -ir content_translation_update_definitions core and found it declared in 3 migration yml files but not anywhere else.

Further exploration shows that content_translation_update_definitions was added in #2225775: Migrate Drupal 6 core node translation to Drupal 8 and later removed in #2599228: Programmatically created translatable content type returns SQL error on content creation.

I don't think any of the three migrations were committed at the time that the property was removed. I suspect these migrations started as a copy paste of the migrations added in #2225775: Migrate Drupal 6 core node translation to Drupal 8 and the use of the property,or lack thereof, was never questioned or tested.

Original IS
d6_language_content_settings.yml, d7_language_content_settings.yml, and d7_node_translation.yml all have a property content_translation_update_definitions on the destination, which set to node. I'm not sure what the purpose of the setting is but it implies that it should be changed for other entities. It seems like for other entities one would copy the migration and change that destination property. Would it not be more flexible to have this as a property in the pipeline?

destination:
  content_translation_update_definitions:
    - node

And note that the source uses a constant value of node for the entity type. While that is a similar problem, it is a much more common pattern and the entity type property is in the pipeline and therefor easier to modify.

Proposed resolution

Remove usage of content_translation_update_definitions in destination plugins.