Remove uses of dynamic_cast from qualifierst hierarchy

[tautschnig]

There is no need to use virtual methods as we always know from context the exact type we are working with.

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

Attention: Patch coverage is 74.28571% with 9 lines in your changes missing coverage. Please review.

Project coverage is 78.04%. Comparing base (b335979) to head (02ae48e).
Report is 2 commits behind head on develop.

Files	Patch %	Lines
jbmc/src/java_bytecode/java_qualifiers.cpp	0.00%	7 Missing ⚠️
src/ansi-c/c_qualifiers.h	92.85%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8405      +/-   ##
===========================================
+ Coverage    78.02%   78.04%   +0.02%     
===========================================
  Files         1726     1726              
  Lines       189442   189388      -54     
  Branches     18466    18466              
===========================================
+ Hits        147808   147809       +1     
+ Misses       41634    41579      -55     

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