Revert "bulidbucket: check service account file existance" 
Revert "bulidbucket: check service account file existance" 

This reverts commit d01ea7ad4521bcfc298d5898febd6b612da10102
https://codereview.chromium.org/865493003/

TBR=vadimsh@chromium.org

Review URL: https://codereview.chromium.org/871713004

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@293769 0039d316-1c4b-4281-b951-d872f2087c98

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