jobs/tools/dockerfiles: Enable to trigger builds remotely
Docker images for running Jenkins jobs will now be rebuilt each time a commit
is pushed to the swh-jenkins-dockerfiles
git repository.
The Herald rule (https://forge.softwareheritage.org/H25) Phabricator side was correctly setup but the Jenkins job configuration was missing an option to allow triggering buils remotely.
Migrated from D4112 (view on Phabricator)