Fix filter popup not closing

[frode-aarstad]

Issue Resolves #8380

Approach Short description of the approach

(Screenshot of new behavior in GUI if applicable)

• [ ] PR title captures the intent of the changes, and is fitting for release notes.
• [ ] Added appropriate release note label
• [ ] Commit history is consistent and clean, in line with the contribution guidelines.
• [ ] Make sure tests pass locally (after every commit!)

When applicable

• [ ] When there are user facing changes: Updated documentation
• [ ] New behavior or changes to existing untested code: Ensured that unit tests are added (See Ground Rules).
• [ ] Large PR: Prepare changes in small commits for more convenient review
• [ ] Bug fix: Add regression test for the bug
• [ ] Bug fix: Create Backport PR to latest release

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 90.87%. Comparing base (50a9869) to head (a03c86d). Report is 11 commits behind head on main.

Files	Patch %	Lines
src/ert/gui/tools/plot/filter_popup.py	50.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #8390 +/- ## ========================================== - Coverage 90.88% 90.87% -0.01% ========================================== Files 347 347 Lines 21076 21068 -8 ========================================== - Hits 19154 19145 -9 - Misses 1922 1923 +1 ```

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