[hooks] fix start_period_tests due to a change of API in vcsfile HGRepo.branch_heads may return draft changesets. Also make start_period_tests return the list of the started TE eids. The test StartTestTC.launch_all_tests() method has also been updated to ask head revisions to the hg hgepo itself iinstead of trying to compute it from database.

"""cubicweb-apycot"""
from cubicweb.schema import ETYPE_NAME_MAP
ETYPE_NAME_MAP['TestConfigGroup'] = 'TestConfig'