Summary:
Our SC release job failed when submitting directly from the prepare-release script, as the jf context wasn't properly setup. So instead we reuse the code we already have for that in SandcastleFlipperAutoReleaseCommand.
However, for manual releases we still do submit automatically and in name of the current user.
Reviewed By: passy
Differential Revision: D20384247
fbshipit-source-id: ed5eca180f009611f2890f8cb665bf203789d189