m1v2,m2v2,metautils: refactoring and meta1 service events

Refactor the notification system and add meta1 notifications
about linked services. Fatorize code duplicated in meta1v2
and meta2v2 (now in sqlx_service_extras).

Enable the notifications in conscience configuration with
  param_option.event_config.meta1 = kafka_enabled=true;kafka_topic=redc.meta1

Change-Id: I4d6b0ac6917a900e4ed4ebfbcfa4c1ab1cdcba41
meta2-mover: wait before retries when defreezing container
metautils: improve error message when deserialization fails

(cherry picked from commit 2fc8e027212c69898661327a23cde4f5333dd201)

Change-Id: I782957322fee3bb3455e5e68aca8e50a471d7eb0