attempt mongo ndjson serialize fix

[seanstory]

closes #1605

Attempts to handle DBRef bson types, to avoid NDJSON serialization errors from the elasticsearch-python client.
Also adds stacktrace logging for when callback coroutines log errors.

Checklists

Pre-Review Checklist

• this PR has a meaningful title
• this PR links to all relevant github issues that it fixes or partially addresses
• if there is no GH issue, please create it. Each PR should have a link to an issue
• this PR has a thorough description
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• Added a label for each target release version (example: v7.13.2, v7.14.0, v8.0.0)
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Release Note

Fixes a bug where Mongodb records containing BSON DBRef fields could not be indexed to Elasticsearch and caused sync failures.

[artem-shelkovnikov]

Good stuff, @seanstory wanna test and merge?

[artem-shelkovnikov]

@seanstory do you wanna merge this?

[seanstory]

Yeah let's go ahead. I haven't heard back from the community member who reported, but even if this doesn't fix the root issue, it's an improvement.

[github-actions]

💚 Backport PR(s) successfully created

Status	Branch	Result
✅	8.11	#1927

This backport PR will be merged automatically after passing CI.