BUG/MINOR: sample: make quic_enabled() always succeed

BUG/MINOR: sample: make quic_enabled() always succeed

smp_fetch_quic_enabled() ends with "return smp->data.u.sint" instead of
"return 1", so it returns its boolean result as the success status of
the fetch as well. On a build without QUIC, or when the QUIC listeners
are disabled, the fetch therefore fails instead of reporting a false
boolean, and any expression using it fails to evaluate.

The issue was introduced in 2.8-dev2 with commit 33d11c464f ("MINOR:
sample: Add "quic_enabled" sample fetch") so this fix should be
backported to 2.8.