Revert "[clang] Speedup line offset mapping computation"

This reverts commit 6951b72334bbe4c189c71751edc1e361d7b5632c.
Breaks several bots, see comments on https://reviews.llvm.org/D99409

GitOrigin-RevId: c22b09debddbaa00be3418b47ca33446ee8a8319
1 file changed