Contracts (DFCC) regression tests: use CaDiCaL

[tautschnig]

Using CaDiCaL as SAT solver (when available) instead of MiniSat reduces test execution time from 337 seconds down to 131 seconds (with only a single test now taking more than 2 seconds, where its 6 seconds are mainly spent in symex).

• Each commit message has a non-empty body, explaining why the change was made.
• 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).
• 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

All modified and coverable lines are covered by tests ✅

Project coverage is 77.94%. Comparing base (0760cd7) to head (4fd1cf8).
Report is 8 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8414   +/-   ##
========================================
  Coverage    77.94%   77.94%           
========================================
  Files         1726     1726           
  Lines       189624   189624           
  Branches     18257    18258    +1     
========================================
  Hits        147801   147801           
  Misses       41823    41823           

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