Update card collapsed state handling to change child view model visibility attribute

[dalthviz]

For an initial description of the approach followed for the proposed change you can check https://github.com/holoviz/panel/issues/8198#issuecomment-3437967199

Fixes #8198

[codecov[bot]]

Codecov Report

:white_check_mark: All modified and coverable lines are covered by tests. :white_check_mark: Project coverage is 85.93%. Comparing base (d93db73) to head (6abc4ea). :warning: Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8274      +/-   ##
==========================================
- Coverage   86.01%   85.93%   -0.08%     
==========================================
  Files         349      349              
  Lines       54647    54660      +13     
==========================================
- Hits        47004    46972      -32     
- Misses       7643     7688      +45     

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[dalthviz]

Note: Closing and reopening to check if a CI rerun helps with the failing test_server_thread_pool_change_event[tornado] test

[philippjfr]

That one is flaky and unrelated.

[dalthviz]

Yep, in my last commit I added a flaky decorator to that test and CI now is green. Let me know if there is something else that should be done here or if that last change I did should be reverted/moved to a different PR!

[dalthviz]

Note: Closing and reopening to retrigger CI