Enable bot_update_test.py for precommit only.
Enable bot_update_test.py for precommit only.

The test can take a long time to run, so skip it for pre-upload.

BUG=

Review URL: https://codereview.chromium.org/326213002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@278098 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build