Remove unused {c,java}_qualifierst::count

[tautschnig]

These are never used (and their implementation was awkwardly summing up Booleans, yielding conversion warnings).

• 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).
• 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

All modified and coverable lines are covered by tests ✅

Project coverage is 78.70%. Comparing base (66004dc) to head (0e1bdf5).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8583      +/-   ##
===========================================
- Coverage    78.71%   78.70%   -0.01%     
===========================================
  Files         1732     1732              
  Lines       199536   199541       +5     
  Branches     18281    18249      -32     
===========================================
  Hits        157057   157057              
- Misses       42479    42484       +5     

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