jaeger: fix download on musl-based systems

What does this Merge Request do?

In order to set up jaeger, we check the OSTYPE variable and choose the correct binary archive to download. We currently support both glibc-based Linux systems as well as macOS, but this leaves out some more exotic platforms like musl-based Linux.

Recognize "linux-musl" and treat it the same as "linux-gnu". The binaries contained in the archive are statically linked anyway and thus do not depend on any external libc, making them work on both glibc- and musl-based systems.

Merge Request checklist

• Tests added for new functionality. If not, please raise Issue to follow-up.
• This change is backward compatible. If not, please include steps to communicate to our users.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.