fix(GlFilteredSearch): allow passing null values to non multi select inputs

See merge request gitlab-org/gitlab-ui!4859



Merged-by: Mark Florian <mflorian@gitlab.com>
Approved-by: Lorenz van Herwaarden <lvanherwaarden@gitlab.com>
Approved-by: Mark Florian <mflorian@gitlab.com>
Reviewed-by: Mark Florian <mflorian@gitlab.com>
Reviewed-by: Lorenz van Herwaarden <lvanherwaarden@gitlab.com>
Co-authored-by: Savas Vedova <svedova@gitlab.com>

## [105.1.1](gitlab-org/gitlab-ui@v105.1.0...v105.1.1) (2024-12-10)

### Bug Fixes

* **GlFilteredSearch:** allow passing null values to non multi select inputs ([01446a98](gitlab-org/gitlab-ui@01446a98))