ViewAlgs: Make sure usedROIMatchingFlag is initialized
This fixes the error:
Conditional jump or move depends on uninitialised value(s)
at 0x1881D067D: checkCache (EventViewCreatorAlgorithm.cxx:184)
by 0x1881D067D: EventViewCreatorAlgorithm::checkCache(DataVector<xAOD::TrigComposite_v1, DataModel_detail::NoBase> const*, xAOD::TrigComposite_v1 const*, unsigned long&, InputMakerBase::MatchingCache&, EventContext const&) const (EventViewCreatorAlgorithm.cxx:177)
by 0x1881D9109: EventViewCreatorAlgorithm::execute(EventContext const&) const (EventViewCreatorAlgorithm.cxx:104)
cc: @tamartin