[clang-format] Inconsistent behavior regarding line break before access modifier

Fixes https://llvm.org/PR41870.

Checks for newlines in option Style.EmptyLineBeforeAccessModifier are now based on the formatted new lines and not on the new lines in the file.

Reviewed By: HazardyKnusperkeks, curdeius

Differential Revision: https://reviews.llvm.org/D99503

GitOrigin-RevId: fd4e08aa8f7edfe877d022859ce162a1b4fa684c