Revert of Add a DEPS gclient hook to prune corrupt mockito remote. (patchset #1 id:1 of https://codereview.webrtc.org/2326523002/ )

Reason for revert:
Unfortunately this didn't help, so I'm reverting this to clean things up for now.

Original issue's description:
> Add a DEPS gclient hook to prune corrupt mockito remote.
>
> A third_party remote for third_party/mockito/src is corrupt. Run
> `git remote prune origin` in the checkout directory before syncing
> Chromium.
>
> Thanks to slan@ for providing this fix.
>
> TBR=kjellander@webrtc.org
> BUG=chromium:644722
> NOTRY=True
>
> Committed: https://crrev.com/3115b06957d5b8cba5d45cebc301795e94a926ec
> Cr-Commit-Position: refs/heads/master@{#14138}

TBR=ehmaldonado@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=chromium:644722

Review-Url: https://codereview.webrtc.org/2326473003
Cr-Commit-Position: refs/heads/master@{#14143}

sync_chromium.py

@@ -31,7 +31,7 @@ import textwrap
 
 # Bump this whenever the algorithm changes and you need bots/devs to re-sync,
 # ignoring the .last_sync_chromium file
-SCRIPT_VERSION = 9
+SCRIPT_VERSION = 8
 
 ROOT_DIR = os.path.dirname(os.path.abspath(__file__))
 CHROMIUM_NO_HISTORY = 'CHROMIUM_NO_HISTORY'