[FIX] validate input value symmetric_cbar

[Remi-Gau]

• Closes none but relates to [BUG] avg_method and symmetric_cbar flags using plot_surf_stat_map working properly with plotly engine #4296 (comment)

Changes proposed in this pull request:

• add input validation of the symmetric_cbar parameters to functions that use it
• add test

[github-actions]

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[codecov]

Codecov Report

Attention: Patch coverage is 71.42857% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 92.13%. Comparing base (abb80ff) to head (3da4a7d).
Report is 37 commits behind head on main.

Files	Patch %	Lines
nilearn/_utils/param_validation.py	50.00%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4339      +/-   ##
==========================================
+ Coverage   91.85%   92.13%   +0.28%     
==========================================
  Files         144      143       -1     
  Lines       16419    16509      +90     
  Branches     3434     3466      +32     
==========================================
+ Hits        15082    15211     +129     
+ Misses        792      751      -41     
- Partials      545      547       +2     

Flag	Coverage Δ
macos-latest_3.11_test_plotting	91.93% <71.42%> (+0.07%)	⬆️
macos-latest_3.12_test_plotting	91.93% <71.42%> (?)
ubuntu-latest_3.10_test_plotting	91.93% <71.42%> (+0.07%)	⬆️
ubuntu-latest_3.11_test_plotting	91.93% <71.42%> (?)
ubuntu-latest_3.12_test_plotting	91.93% <71.42%> (?)
ubuntu-latest_3.8_test_min	68.78% <7.14%> (?)
ubuntu-latest_3.8_test_plot_min	91.59% <71.42%> (?)
ubuntu-latest_3.8_test_plotting	91.89% <71.42%> (?)
ubuntu-latest_3.9_test_plotting	91.89% <71.42%> (?)
windows-latest_3.10_test_plotting	91.90% <71.42%> (?)
windows-latest_3.11_test_plotting	91.90% <71.42%> (?)
windows-latest_3.12_test_plotting	91.90% <71.42%> (?)
windows-latest_3.8_test_plotting	91.86% <71.42%> (?)
windows-latest_3.9_test_plotting	91.87% <71.42%> (?)

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