When cycling through searched results, up and down on the keyboard cycles through all packages which are not displayed.

Expected: To cycle through only my searched results.

Steps to reproduce.
- Open Unity and navigate to Windows > Package Manager.
- Type "verified" into the top right search bar.
- Verified packages now appear in the left hand panel.
- Select the top package.
- Use the down arrow on your keyboard to cycle through the list of packages.
NOTICE ISSUE >> I'm now cycling through all packages. I would expect to only cycle through what is listed.

Seems to be a regression on package manager UI 2018.3.12f1. Package Version 2.0.7

Working: 2018.3.12f1. Package Version 2.0.7
Broken: 2019.2.0a11, 2019.1.0b2. Package Version: 2.2.0, 2.1.1.