Improve logs for sending updates on the distributor side

$title.

Currently the output is like

```
2020-07-24 18:22:11,709 INFO [eclk/distributor] - Result notification received for FAKE_ELECTION/R_V/01A
2020-07-24 18:22:11,734 INFO [eclk/distributor] - Result data received for FAKE_ELECTION/R_V/01A
2020-07-24 18:22:11,805 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
2020-07-24 18:22:11,809 INFO [eclk/distributor] - Publishing cumulative result with FAKE_ELECTION/R_VI/01A
2020-07-24 18:22:11,869 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
2020-07-24 18:22:21,899 INFO [eclk/distributor] - Result notification received for FAKE_ELECTION/R_V/01B
2020-07-24 18:22:21,908 INFO [eclk/distributor] - Result data received for FAKE_ELECTION/R_V/01B
2020-07-24 18:22:21,966 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
2020-07-24 18:22:21,968 INFO [eclk/distributor] - Publishing cumulative result with FAKE_ELECTION/R_VI/01B
2020-07-24 18:22:22,019 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
2020-07-24 18:22:32,069 INFO [eclk/distributor] - Result notification received for FAKE_ELECTION/R_V/01PV
2020-07-24 18:22:32,089 INFO [eclk/distributor] - Result data received for FAKE_ELECTION/R_V/01PV
2020-07-24 18:22:32,142 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
2020-07-24 18:22:32,144 INFO [eclk/distributor] - Publishing cumulative result with FAKE_ELECTION/R_VI/01PV
2020-07-24 18:22:32,209 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
2020-07-24 18:22:42,235 INFO [eclk/distributor] - Result notification received for FAKE_ELECTION/R_V/02J
2020-07-24 18:22:42,305 INFO [eclk/distributor] - Result data received for FAKE_ELECTION/R_V/02J
2020-07-24 18:22:42,359 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
2020-07-24 18:22:42,362 INFO [eclk/distributor] - Publishing cumulative result with FAKE_ELECTION/R_VI/02J
2020-07-24 18:22:42,420 INFO [eclk/distributor] - Sending JSON data for 2816adfffe493860-000052a0-00000004-1283ac087d8bf22b-da506601
```

The issue identifies the distributor logging path but names no files, tests, or entry points. Start by locating the code that emits the example messages and inspect how update-sending events are currently logged. Done should be a concrete, agreed logging improvement that makes those events easier to distinguish.

Written by the indexing model from the issue text.