update labels for fat_bands

[AndresOrtegaGuerrero]

In #787 ,
I forgot to update the logic for the fat_bands , here is included
Now for only bands calculations and fat bands the labels are propertly display

[codecov]

Codecov Report

Attention: Patch coverage is 25.00000% with 6 lines in your changes missing coverage. Please review.

Project coverage is 68.07%. Comparing base (860f59b) to head (1ba25e3).
Report is 88 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aiidalab_qe/common/bandpdoswidget.py	25.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #842      +/-   ##
==========================================
- Coverage   68.12%   68.07%   -0.05%     
==========================================
  Files          50       50              
  Lines        4555     4561       +6     
==========================================
+ Hits         3103     3105       +2     
- Misses       1452     1456       +4     

Flag	Coverage Δ
python-3.11	68.07% <25.00%> (-0.05%)	⬇️
python-3.9	68.10% <25.00%> (-0.05%)	⬇️

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[mikibonacci]

Hi @AndresOrtegaGuerrero , for me can be merged! We should keep in mind to have some tests in the future, but for now it is not so crucial.

Thanks!