Elastic Java APM Agent breaks trace logging for SpringBoot

Please find below description along with repo and reproduction steps.

## Describe the bug
Trace id in log line is missing when using APM Java agent.

## Steps to reproduce
1. Use code from repo: https://github.com/nefsir/apm-trace-id-issue
2. Run project and call /dummy endpoint. Log line contains trace id.
3. Instrument with latest APM (-javaagent:{path-to-agent}/elastic-apm-agent.jar, version that I use is added to repository).
4. Run project and call /dummy endpoint. Log line does not contain trace id.

## Expected behavior
Instrumentation does not impact trace id logging.