Apex: Fix CSIT snapshot files path

With the refactor of snapshot pipeline to include other snapshots, the
path had changed to be generic for where temporary snapshot files are
stored (from /tmp/csit to /tmp/snap). See this commit:

https://gerrit.opnfv.org/gerrit/#/c/65157/4/jjb/apex/apex-fetch-snap-info.sh

This patch fixes the path for triggering CSIT job.

Change-Id: I63308d73c13e8c714078a38bc6cf9bb75cbeec5c
Signed-off-by: Tim Rozet <trozet@redhat.com>