Fix: remote kernel stream paths contain too much information

The kernel stream paths, when built with a "net" consumer type,
contain the hostname and session name. This is redundant and must not
be transmitted to 2.11+ relay daemons. Otherwise, this results in an
erronerous path hierarchy on the remote end.

Stream paths transmitted to a trace chunk-aware peer are relative to a
session's output trace chunk.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>