Previously, we would use the count of the string `goroutine ` as a
proxy for the number of goroutines in the stacktrace. This stopped
working in go 1.21 due to this change:
https://github.com/golang/go/commit/51225f6fc648ba3e833f3493700c2996a816bdaa

We should consider using a stacktrace parser in the future.

Supports #112088

Epic: None
Release note: None