[Windows] Fix warning C4477 + code formatting (#18502)

* [Windows] Fix warning C4477 + code formatting

Fix the following warning:
IoBigEventGeneration.cxx(355): warning C4477: 'printf' : format string '%ld' requires an argument of type 'long', but variadic argument 1 has type 'unsigned __int64'
IoBigEventGeneration.cxx(355): note: consider using '%zd' in the format string

* [clang-format] formatting

Author: bellenot