[clang-format] PR42434 Remove preprocessor and pragma lines from ObjectiveC guess

clang-format see the `disable:` in   __pragma(warning(disable:)) as ObjectiveC method call

Remove any line starting with `#` or __pragma line from being part of the ObjectiveC guess

https://bugs.llvm.org/show_bug.cgi?id=42434

Reviewed By: curdeius, krasimir

Differential Revision: https://reviews.llvm.org/D92922