[Feature] - Insert events into preloaded logs

[Henning-Schulz]

Is your feature request related to a problem? Please describe.
The new agent command to retrieve logs is nice, but I would like to know better when some relevant events happened when viewing the logs. For example, when a new instrumentation config was fetched, old instrumentation logs get outdated. However, the default log-preloading config only considers WARN and ERROR logs, which don't contain the INFO messages about newly applied instrumentation.

Describe the solution you'd like
I would like the agent to put artificial log entries into the preloaded logs that mark certain events (such as instrumentation) occur.

Describe alternatives you've considered
An alternative would be to throw away instrumentation logs whenever new instrumentations are applied, which is however very complex to realize. Also, we don't really benefit from throwing away the logs and there might be edge cases where the "outdated" logs are still interesting.

Additional context
As we plan to connect the log retrieval with a health status indicator, the artificial log entries will also help understanding the current health, as it is based on the same logs and events.