Drop Title Case In Ert Gui

[berland]

Title Case were inconsistently in use in various GUI elements. This commit
removes All Of Them, except Ensemble Reservoir Toolbox.

[codecov-commenter]

Codecov Report

Merging #3190 (42d1e42) into main (63fe884) will decrease coverage by 0.01%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##             main    #3190      +/-   ##
==========================================
- Coverage   65.53%   65.52%   -0.02%     
==========================================
  Files         610      610              
  Lines       48975    48975              
  Branches     4403     4403              
==========================================
- Hits        32095    32089       -6     
- Misses      15413    15415       +2     
- Partials     1467     1471       +4     

Impacted Files	Coverage Δ
ert_gui/ertwidgets/caselist.py	24.00% <0.00%> (ø)
.../ertwidgets/models/analysismodulevariablesmodel.py	56.81% <ø> (ø)
ert_gui/gert_main.py	96.00% <ø> (ø)
..._gui/tools/manage_cases/case_init_configuration.py	14.18% <0.00%> (ø)
ert_gui/tools/manage_cases/manage_cases_tool.py	76.92% <0.00%> (ø)
...tools/plot/customize/default_customization_view.py	30.23% <0.00%> (ø)
.../tools/plot/customize/limits_customization_view.py	24.32% <0.00%> (ø)
...ls/plot/customize/statistics_customization_view.py	20.68% <ø> (ø)
...i/tools/plot/customize/style_customization_view.py	30.76% <0.00%> (ø)
ert_gui/tools/plot/filter_popup.py	23.07% <0.00%> (ø)
... and 24 more

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[sondreso]

Consistency is the foundation of virtue.

- Francis Bacon