Make trusty logstash-filter jobs voting
Make trusty logstash-filter jobs voting

These jobs are now stable, make them voting.

Change-Id: I5d7f021e970d68fbc6af3c63225041032fb3835e
Depends-On: Ic1ab6d04232abb3cf347f0d27afbf9172f62b0e4

openstack-infra/project-config,openstack-infra/project-config