Revert "Bug 1092195 - Investigate failure in test_cost_control_ftu.py"

This reverts commit 07f5ea2d845d6d17c05c388090b77528ac87ddb4.
Bug 1095638 - Split resolve/reject cases in chai-as-promised test r=julienw
Bug 1095638 - merge pull request #25945 from KevinGrandon:bug_1095638_chai_split_test to mozilla-b2g:master