Remove unnecessary view filter and create upgrade path to entity_usage native solution

The 5.x entity_usage module allows for filtering for content that is entirely unreferenced without needing this module's filter. It can be accomplished by:

• Create a view of content entities. (If using a view of content revisions, you will need an additional relationship on the content entity.)
• Add a relationship of "Usage information". Leave "Require this relationship" unchecked.
• Using that relationship, add a filter for "Entity Usage: Usage count" is empty.

Since the view filter is no longer needed, remove the filter and add an update hook to use the above approach for sites using the existing filter.

Original support post:

Am I mistaken in my belief that we can effectively provide the same Views filtering feature anyway simply be using a combination of a Relationship and Filter criteria as shown in a View I built below...

Unless I am deluded, this does exactly what I want, i.e. it shows me any and all entities with a Usage count of ZERO...