TrigTauRec: remove TauEventData (ATLASRECTS-3078)

In this MR, we remove the use of TauEventData in trigger.

The VertexContainer and TrackParticleContainer are retrieved via ReadHandle for both offline and online MT version. In online MT version, the key name of these containers depends on the configurations of parent algorithms. To make sure the tools, i.e. TauVertexFinder and TauTrackFinder, have the correct key name, we reset them in TrigTauRecMergedMT::initialize() (before the initialization of these tools). For online non-MT version, these containers are passed as parameters of the execute functions. It is a temporary fix, and will be revisited when/if the non-MT version will no longer be used.