[DNM] Test a self self transformation with different charges

[IAlibay]

Benzene->Toluene has the right partial charges in the core region
Benzene->Benzene does not

Checklist

• Added a news entry

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[github-actions]

No API break detected ✅

[codecov]

Codecov Report

❌ Patch coverage is 93.75000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.86%. Comparing base (eef438f) to head (0efb505).
⚠️ Report is 378 commits behind head on main.

Files with missing lines	Patch %	Lines
openfe/protocols/openmm_rfe/equil_rfe_methods.py	77.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1116      +/-   ##
==========================================
- Coverage   93.51%   91.86%   -1.66%     
==========================================
  Files         142      142              
  Lines       10608    10617       +9     
==========================================
- Hits         9920     9753     -167     
- Misses        688      864     +176     

Flag	Coverage Δ
fast-tests	91.86% <93.75%> (?)
slow-tests	?

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