Remove TERM=dumb, which is causing difficult-to-reproduce hangs
Ref T7119. Three users have now reported that this causes their systems to hang, so it's looking like the cure is worse than the disease.
Revert this until we can eventually reproduce and understand the hang.
Test Plan: Users running into issues have reported that this resolves things.
Reviewed By: btrahan
Maniphest Tasks: T7119
Differential Revision: https://secure.phabricator.com/D11644