Symex: Simplify left-hand side

[tautschnig]

With #7622 we may have syntactically changed the type on the right-hand side via simplification. To maintain syntactic type equality we need to apply simplifications on the left-hand side as well. See https://github.com/awslabs/aws-c-common/actions/runs/4822448417 for an example where this failed after #7622.

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• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.02 ⚠️

Comparison is base (cafbcc4) 78.50% compared to head (dec8c60) 78.48%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7700      +/-   ##
===========================================
- Coverage    78.50%   78.48%   -0.02%     
===========================================
  Files         1674     1674              
  Lines       191954   191956       +2     
===========================================
- Hits        150698   150666      -32     
- Misses       41256    41290      +34     

Impacted Files	Coverage Δ
src/goto-symex/goto_symex_state.cpp	91.86% <100.00%> (+0.04%)	⬆️

... and 1 file with indirect coverage changes

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[peterschrammel]

Is there a test that exhibits the problem?

[tautschnig]

Is there a test that exhibits the problem?

I will try to craft one (the aws-c-common example is too big a code base for a regression test).