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 47.51%. Comparing base (67340b1) to head (43db455).

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%   47.51%           
=======================================
  Files         141      141           
  Lines       29487    29479    -8     
=======================================
- Hits        14010    14008    -2     
+ Misses      15477    15471    -6     

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[timothy-nunn]

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

[timothy-nunn]

Suggested change

	* (55) Vacuum vessel helium concentration upper limit #REMOVED i_blanket_type =2 (itv 96,93,94) #REMOVED
	* (55) NOT USED