Eliminate event type when pushing events to Convoy.

[subomi]

When pushing events to Convoy, it is required to supply the event_type. This has become unnecessary because

1. With our ingesters, we want to receive events from just anybody. This will require us to describe everyone's payload structure to retrieve the event type. This will be too rigid.
2. The essence of having the event_type in the beginning was to enable a decent UI that shows the event_type. We should replace this with event id E.g. event_89hh89hh98h8h98h
3. The other reason we had this field specified is so we can filter by it. But since we are build a more robust search, this will still be possible in the future.