fix: rename the payload parameter in telemetry requests (#299)

Description

Rename the payload parameter in telemetry requests because the current request body contains other field names.

{ 
  "instance_id": text, 
  "event_type": text, 
  "event_data": json
}

See the telemetry_event function:

# \df v1.telemetry_event
                                                   List of functions
 Schema |      Name       | Result data type |                       Argument data types                        | Type 
--------+-----------------+------------------+------------------------------------------------------------------+------
 v1     | telemetry_event | json             | instance_id text, event_type text, event_data json, OUT res json | func
(1 row)

Related issue

#299 (closed)

Examples

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes, specifications reflect those changes and they have been reviewed OR there are no API changes

Closes #299 (closed)