[pino] Omit misleading context when executed in thread-stream worker

[PetrHeinz]

Fixes #124

Unfortunately, the code is executed inside thread-stream worker and doesn't have access to stack trace or the main file name.

I'm keeping the functionality provided the data can be accessed, it might work in a specific Pino version or with a specific setting. If the stackContextHint is not recognized in stack trace, omit the context data.

Only affects Pino.

Before:

After:

[curusarn]

Thanks! Odd that it doesn't work. I think I remember the context working with Pino but maybe I'm wrong.