fix: correct meltano config behavior when explicit environment is provided

[cjohnhanson]

Closes #6512

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[codecov]

Codecov Report

Merging #6997 (e29e558) into main (927fc0f) will decrease coverage by 0.02%.
The diff coverage is 68.96%.

@@            Coverage Diff             @@
##             main    #6997      +/-   ##
==========================================
- Coverage   88.68%   88.66%   -0.03%     
==========================================
  Files         292      292              
  Lines       21278    21307      +29     
  Branches     2101     2105       +4     
==========================================
+ Hits        18871    18892      +21     
- Misses       2052     2059       +7     
- Partials      355      356       +1     

Impacted Files	Coverage Δ
src/meltano/cli/config.py	70.37% <68.00%> (-0.28%)	⬇️
tests/meltano/cli/test_config.py	89.47% <75.00%> (-0.81%)	⬇️
src/meltano/core/plugin_discovery_service.py	89.34% <0.00%> (+0.59%)	⬆️

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