[ci] Remove files from autoscaling job definition (#267)

The `files` attribute on a job means that the job will only run if a
file from that list is changed.
The autoscaling job definition includes this, and the list of files
is specific to the FVT repo. This means that the job will not run in
other repos that do not have these matching files.

The files attribute has been removed from the job definition and added
to the project definition so that it is only applicable when run in the
github-check pipeline for the FVT repo. This allows the job to run in
other repos (i.e. openstack-k8s-operators/telemetry-operator) that can
configure their own rules for what file changes trigger the jobs to run.

Author: elfiesmelfie

.zuul.yaml

@@ -49,11 +49,6 @@
       - roles/test_sensubility/.*
       - roles/test_snmp_traps/.*
       - roles/test_verify_email/.*
-    files:
-      - roles/telemetry_verify_metrics/.*
-      - .zuul.yaml
-      - ci/vars-metric-verification-test.yml
-      - ci/report_result.yml
 
 - job:
     name: functional-tests-on-osp18