Run the `clang-format.bash` script to update all our C and C++ code to a
new style defined by `.clang-format`, now with "east const" enforcement.
Use `clang-format` version 18.
* If you reached this commit for a line in `git blame`, re-run the blame
operation starting at the parent of this commit to see older history
for the content.
* See the parent commit for instructions to rebase a change across this
style transition commit.
Issue: #26123
Newer Python versions (namely 3.13) do not support old compilers before
gcc 4.8 for atomics, which leads to compile errors in the test case.
Since the test actually does not use any of that API, restrict it to the
limited Python API which offers even more stability across versions.
