Removing --pdf_path flag from bisect-builds.py
Removing --pdf_path flag from bisect-builds.py

This is revert of https://codereview.chromium.org/395363002/
Option is not useful any more, we have pdf in chromium more than a year.

R=jam@chromium.org,thestig@chromium.org
BUG=395687

Review URL: https://codereview.chromium.org/1210023004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#337412}

lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,CapOM/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,lihui7115/ChromiumGStreamerBackend,ltilve/ChromiumGStreamerBackend