test: add test case for contract migration with non-trivial migration data

[cgorenflo]

No description provided.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 63.82979% with 17 lines in your changes missing coverage. Please review.

Project coverage is 93.60%. Comparing base (8798898) to head (8fbc4f7).

Files with missing lines	Patch %	Lines
...erfaces/testdata/contract_non_trivial_migration.rs	19.04%	17 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #113      +/-   ##
==========================================
- Coverage   94.13%   93.60%   -0.53%     
==========================================
  Files          48       49       +1     
  Lines        2744     2785      +41     
==========================================
+ Hits         2583     2607      +24     
- Misses        161      178      +17     

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