Remove deleted feature from config file

[ob]

9455445 removed the requeue_on_failure config option but left it in the examples. If you just try to naively use the example, it fails with an exception.

For now, just remove the config line, but the error message could be better.

Exception in thread "main" com.google.protobuf.TextFormat$ParseException: 69:1: Input contains unknown fields and/or extensions:
69:1:	build.buildfarm.v1test.WorkerConfig.requeue_on_failure
	at com.google.protobuf.TextFormat$Parser.checkUnknownFields(TextFormat.java:1405)
	at com.google.protobuf.TextFormat$Parser.merge(TextFormat.java:1428)
	at com.google.protobuf.TextFormat$Parser.merge(TextFormat.java:1364)
	at com.google.protobuf.TextFormat$Parser.merge(TextFormat.java:1334)
	at com.google.protobuf.TextFormat.merge(TextFormat.java:1213)
	at build.buildfarm.worker.operationqueue.Worker.toWorkerConfig(Worker.java:515)
	at build.buildfarm.worker.operationqueue.Worker.main(Worker.java:543)

[werkt]

good catch, thanks!