chore: improve package resolution at `agent.start()`

When the agent starts with `logLevel = trace` the agent tries to resolve the package info to display some extra data by doing a simple file lookup in the running scripts folder. It is possible that the script is not placed alongside the package file but it might be on a upper level.

We need to improve the lookup process to cover this situation. For more context see [this comment](https://github.com/elastic/apm-agent-nodejs/pull/3383/files#r1212187394)