🔧 Remove unused configuration variables

[chrisjsewell]

Remove defined configuration variables that are not used anywhere in the codebase. I guess these are legacy configurations that were used once but no more.

[codecov]

Codecov Report

Attention: Patch coverage is 97.43590% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.91%. Comparing base (4e10030) to head (30f6971).
Report is 51 commits behind head on master.

Files with missing lines	Patch %	Lines
sphinx_needs/config.py	97.43%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1303      +/-   ##
==========================================
+ Coverage   86.87%   86.91%   +0.03%     
==========================================
  Files          56       60       +4     
  Lines        6532     6946     +414     
==========================================
+ Hits         5675     6037     +362     
- Misses        857      909      +52     

Flag	Coverage Δ
pytests	86.91% <97.43%> (+0.03%)	⬆️

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