Remove numeric suffixes and combine directories in regression/cbmc-library

[tautschnig]

We do not need a one-test-per-directory set-up anymore as nowadays test.pl can safely use multiple tests in a single directory. This avoid indefinitely growing the number of directories, making navigation much harder.

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• 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).
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• My PR is restricted to a single feature or bugfix.
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[Copilot]

Pull request overview

This PR consolidates test files in the regression/cbmc-library directory by removing numeric suffixes and combining tests that were previously separated into individual directories. The changes update test files to properly test builtin infinity functions instead of unrelated library functions.

• Removes the one-test-per-directory requirement to simplify navigation
• Updates test files to call the correct builtin functions they're intended to test
• Corrects include headers to match the actual function being tested

Reviewed changes

Copilot reviewed 3 out of 993 changed files in this pull request and generated no comments.

File	Description
regression/cbmc-library/__builtin_infl/main.c	Updates test to call __builtin_infl() instead of memset() and includes math.h instead of string.h
regression/cbmc-library/__builtin_inff/main.c	Updates test to call __builtin_inff() instead of malloc() and includes math.h instead of stdlib.h
regression/cbmc-library/__builtin_inf/main.c	Updates test to call __builtin_inf() instead of htonl() and includes math.h instead of inet.h

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.00%. Comparing base (945c1e0) to head (90f278f).
⚠️ Report is 3 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8815   +/-   ##
========================================
  Coverage    80.00%   80.00%           
========================================
  Files         1700     1700           
  Lines       188257   188257           
  Branches        73       73           
========================================
  Hits        150615   150615           
  Misses       37642    37642           

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