[dashboard] [native filters] Existing default values get deleted when searching

[geido]

How to reproduce the bug

1. Go to a Dashboard
2. Edit a filter
3. Search for a value in "Default value"
4. Observe that existing default values get deleted

Expected results

Existing default values should remain selected

Actual results

Existing default values get deleted

Screenshots

Unicode.Test.mp4

Environment

(please complete the following information):

• browser type and version: Chrome 97.0.4692.71
• superset version: 1.4.0rc4
• any feature flags active:

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven't found one similar.