7.12 migrations fail on tsvb-validation-telemetry documents

[rudolf]

When using the v1 upgrade migration in 7.12 upgrades can fail with:

Error: Document "tsvb-validation-telemetry" has property "tsvb-validation-telemetry" which belongs to a more recent version of Kibana [7.10.0]. The last known version is [undefined]
at /usr/share/kibana/src/core/server/saved_objects/migrations/core/document_migrator.js:600:27
at Array.find ()
at nextUnmigratedProp (/usr/share/kibana/src/core/server/saved_objects/migrations/core/document_migrator.js:591:21)
at applyMigrations (/usr/share/kibana/src/core/server/saved_objects/migrations/core/document_migrator.js:337:18)
at DocumentMigrator.transformAndValidate [as transformDoc]

This is caused by this saved object type no longer being registered #87848 but only affects v1 migrations (related #56731)

Workaround:

1. Stop Kibana
2. Rollback from the failed migration https://www.elastic.co/guide/en/kibana/7.x/upgrade-migrations.html#upgrade-migrations-rolling-back
3. Delete the document. These documents are no longer used by Kibana so deleting it won't have any impact.
   DELETE .kibana/_doc/tsvb-validation-telemetry:tsvb-validation-telemetry
4. start Kibana

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)