fix: count reduces by 1 for each record deleted

[kwhuber]

Fixes #7494
Fixes #4988

This fix continues a change from pr-7635 to fix a ui issue when a user deletes records through the query builder. Prior to the change, the results header in the returned query would delete records two at a time. This happened because handleDelete was being called twice, hence the need for the deletingRef tracking set.

Checklist

• Self-review the PR after opening it to make sure the changes look good and
  self-explanatory (or properly documented)
• Add relevant issue to release milestone
• Add pr to documentation list
• Add automated tests
• Add a reverse migration if a migration is present in the PR

Testing instructions

• Create a query with at least 2 records
• Delete all the records that show up
• Verify that the results count decreases by 1 following each removal
• Verify that the results count is zero and non-negative once all records are deleted

[kwhuber]

@grantfitzsimmons This pr accounts for the negative issue in addition to the duplicate delete issue. May I close pr-7635 to avoid duplicate fixes?

[emenslin]

• Create a query with at least 2 records
• Delete all the records that show up
• Verify that the results count decreases by 1 following each removal
• Verify that the results count is zero and non-negative once all records are deleted

Looks good!

01-14_11.34.mp4

[Iwantexpresso]

• Create a query with at least 2 records
• Delete all the records that show up
• Verify that the results count decreases by 1 following each removal
• Verify that the results count is zero and non-negative once all records are deleted

nice job!