tools: use cout instead of cerr in journal tool

Aside from being a bit odd to begin with, using stderr
was causing tests to fail because the output was polluted
by log output which is also on stderr.

Fixes: 9281

Signed-off-by: John Spray <john.spray@redhat.com>
Merge pull request #2360 from ceph/wip-9281

tools: use cout instead of cerr in journal tool

Reviewed-by: Sage Weil <sage@redhat.com>