Remove non-existent {f,F}orall_valid_objects from clang-format

[tautschnig]

This macro does not seem to exist in the code base anymore.

• 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/
• n/a 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.

[martin-cs]

Seems sensible.

[codecov]

Codecov Report

Merging #5773 (208d47e) into develop (fb32eb1) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #5773   +/-   ##
========================================
  Coverage    69.67%   69.67%           
========================================
  Files         1248     1248           
  Lines       100836   100836           
========================================
  Hits         70262    70262           
  Misses       30574    30574           

Flag	Coverage Δ
cproversmt2	43.42% <ø> (ø)
regression	66.65% <ø> (ø)
unit	32.20% <ø> (ø)

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