Remove skia/PRESUBMIT.py
Remove skia/PRESUBMIT.py

`git cl try` uses the list of bots in there as exclusive try list.
Since the list of bots in skia/PRESUBMIT.py is a subset of the regular
cq set, just remove the file to make `git cl try` send the usual set
of try jobs instead of just a single one for linux_blink_rel.

BUG=none

Review URL: https://codereview.chromium.org/1877903002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#387993}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk