Remove references to old i_blanket_type types

[athoynilimanew]

Description

closes #4071

@timothy-nunn do we also need to delete variables e.g. densbreed, breedmat that is only used for
i_blanket_type=2?

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 82.14286% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.92%. Comparing base (67340b1) to head (5e35ad1).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
process/models/power.py	0.00%	3 Missing ⚠️
process/models/costs/costs.py	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4124      +/-   ##
==========================================
+ Coverage   47.51%   47.92%   +0.40%     
==========================================
  Files         141      142       +1     
  Lines       29487    29915     +428     
==========================================
+ Hits        14010    14336     +326     
- Misses      15477    15579     +102     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[timothy-nunn]

We can remove the constraint description since the actual constraint has been removed