Allow hiding observations for field parameter plots

[dafeda]

Show observation controls for field plots with observation locations, while hiding unsupported observation and history controls for GEN_KW and surface keys.

• 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 unit tests pass locally after every commit (git rebase -i main --exec 'just rapid-tests')

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: Add backport label to latest release (format: 'backport release-branch-name')

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.59459% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.53%. Comparing base (15477f3) to head (f3c90d0).

Files with missing lines	Patch %	Lines
...ert/gui/tools/plot/customize/customization_view.py	93.33%	1 Missing ⚠️
...tools/plot/customize/default_customization_view.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13623      +/-   ##
==========================================
- Coverage   89.54%   89.53%   -0.02%     
==========================================
  Files         464      464              
  Lines       32779    32815      +36     
==========================================
+ Hits        29353    29381      +28     
- Misses       3426     3434       +8     

Flag	Coverage Δ
cli-tests	35.72% <0.00%> (-0.04%)	⬇️
fuzz	43.92% <21.62%> (-0.03%)	⬇️
gui-tests	59.85% <91.89%> (+0.03%)	⬆️
performance-and-unit-tests	78.08% <94.59%> (+<0.01%)	⬆️
test	45.38% <21.62%> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
.../gui/tools/plot/customize/customize_plot_dialog.py	81.43% <100.00%> (+0.31%)	⬆️
...i/tools/plot/customize/style_customization_view.py	90.14% <100.00%> (+1.25%)	⬆️
src/ert/gui/tools/plot/plottery/plots/std_dev.py	96.05% <100.00%> (ø)
...ert/gui/tools/plot/customize/customization_view.py	88.57% <93.33%> (+0.79%)	⬆️
...tools/plot/customize/default_customization_view.py	82.75% <88.88%> (+1.12%)	⬆️

... and 2 files with indirect coverage changes