Python Integration tests: log test name

When creating a job (on any runner), log the originating test so it's easier to debug.
Postcommits frequently run tens of pipelines at a time and it's getting harder to tell them apart.

By logging I mean putting it somewhere in the job proto (such as in parameter, job name, etc.). Using the worker logger on startup won't work if the worker fails to start.
Ideally you should be able to see the name in the runner UI (such as Dataflow cloud console).