[release] Fix auto-roller.

This removes an unnecessary gclient-sync for chromium, which
makes the bots die when network is slow.

NOTRY=true
TBR=hablich@chromium.org

Review URL: https://codereview.chromium.org/1658043003

Cr-Commit-Position: refs/heads/master@{#33681}

tools/release/auto_roll.py

@@ -123,7 +123,6 @@ class UpdateChromiumCheckout(Step):
     cwd = self._options.chromium
     self.GitCheckout("master", cwd=cwd)
     self.DeleteBranch("work-branch", cwd=cwd)
-    self.Command("gclient", "sync --nohooks", cwd=cwd)
     self.GitPull(cwd=cwd)
 
     # Update v8 remotes.

tools/release/test_scripts.py

@@ -43,8 +43,6 @@ import merge_to_branch
 from merge_to_branch import *
 import push_to_candidates
 from push_to_candidates import *
-import chromium_roll
-from chromium_roll import ChromiumRoll
 import releases
 from releases import Releases
 from auto_tag import AutoTag
@@ -1086,7 +1084,6 @@ deps = {
       Cmd("git status -s -uno", "", cwd=chrome_dir),
       Cmd("git checkout -f master", "", cwd=chrome_dir),
       Cmd("git branch", "", cwd=chrome_dir),
-      Cmd("gclient sync --nohooks", "syncing...", cwd=chrome_dir),
       Cmd("git pull", "", cwd=chrome_dir),
       Cmd("git fetch origin", ""),
       Cmd("git new-branch work-branch", "", cwd=chrome_dir),