fix handling of default dims

[OriolAbril]

Description

We have the concept of default_dims in dict_to_dataset and related functions,
which are dimensions that come at the beginning and can be omitted from the
dims list but they can also be there. This fixes a bug for the case
where the default_dims are present in the dims list (which is necessary
when the default dims are not chain and draw).

Checklist

• Does the PR follow official PR format?
• Does the PR include new or updated tests to prevent issue recurrence (using pytest fixture pattern)?
• Is the code style correct (follows pylint and black guidelines)?
• Is the fix listed in the Maintenance and fixes section of the changelog?

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📚 Documentation preview 📚: https://arviz--2138.org.readthedocs.build/en/2138/

[codecov]

Codecov Report

Merging #2138 (7c26abf) into main (b2503b5) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #2138   +/-   ##
=======================================
  Coverage   90.73%   90.73%           
=======================================
  Files         118      118           
  Lines       12566    12567    +1     
=======================================
+ Hits        11402    11403    +1     
  Misses       1164     1164           

Impacted Files	Coverage Δ
arviz/data/base.py	98.21% <100.00%> (+0.01%)	⬆️

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