Why is Skywalk doorbell on my iPad?

Unless you have a deep understanding of Analytics and associated log files - and have the both means and expert knowledge to decipher their contents - they are best left alone. These logs are largely not intended to be human-readable.

Programmers often use very cryptic tags and terms - that are frequently misinterpreted if taken literally. By example, the "doorbell" entry is very unlikely to have any relationship whatsoever to an actual doorbell.