fix(event): fix since field incorrect

[e11sy]

Problem

Now since day is incorrect, it displays timestamp of the last repetition It happens because we merge payload of the original event with the payload of the repetition (and timestamp overwrites)

Solution

In current realisation we can save timestamp field from the original event payload and make sure, that repetition payload does not overwrite the original timestamp

• Now saving original event timestamp and on repetition merge writing original timestamp to payload

Note

Probably could be solved by moving timestamp out of the payload, but it is not designed