Fix error when cycling the dropdown filter options in advanced search #11442

[MikeGriniezakis]

In the error report, cyling between "references" and "does not reference" produce a "NoneType is not iterable" error. This was due to the fact that when a value is selected in the dropdown, the value is set to null if the string is an empty string.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Description of Change

Cycling between "references" and "does not reference" produces a "NoneType is not iterable" error.
This was due to the fact that when a value is selected in the drop-down, the value is set to null if the string
is an empty string. In the example provided in the issue report, the "references" entry has an id of "".
Upon selecting it, the change event is fired and the value is set to null.

This PR removes the logic that converted the empty string to null when the change event is fired.

Issues Solved

Closes #11442

Checklist

• I targeted one of these branches:
  • dev/8.0.x (under development): features, bugfixes not covered below
  • dev/7.6.x (main support): regressions, crashing bugs, security issues, major bugs in new features
  • dev/6.2.x (extended support): major security issues, data loss issues
• I added a changelog in arches/releases
• I submitted a PR to arches-docs (if appropriate)
• Unit tests pass locally with my changes
• I added tests that prove my fix is effective or that my feature works
• My test fails on the target branch