[opentelemetry] Build test-environment for default log collection

[timojohlo]

Context

Currently, the parsing and shipping of logs have to be tested manually. In order to improve the quality of logs and to allow faster shipping of new features we want to build a test-environment that tests default log configuration.

This ticket depends on #515

Acceptance Criteria

• Define scope: What should be tested
• Define test-environment: Are there any existing tools we can use to test our configs? Do we have to build something ourselves?
• Create tests for parsing, receivers, processors, exporters
• Add Documentation for Testing
• Include testing as automated check e.g. through GitHub Action

References

[timojohlo]

Future improvements:

• also test custom configs
• provide documentation on how to test custom configs