[OPIK-210] Fix NPE in batch endpoint when project name is null

[thiagohora]

Details

Fixing NPE:

error.stack:    at java.base/java.util.Objects.requireNonNull(Objects.java:259)
    at reactor.core.publisher.FluxIterable$IterableSubscription.slowPath(FluxIterable.java:322)
    at reactor.core.publisher.FluxIterable$IterableSubscription.request(FluxIterable.java:294)
    at reactor.core.publisher.FluxFlatMap$FlatMapMain.onSubscribe(FluxFlatMap.java:373)
    at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:201)
    at reactor.core.publisher.FluxIterable.subscribe(FluxIterable.java:83)
    at reactor.core.publisher.Mono.subscribe(Mono.java:4512)
    at reactor.core.publisher.MonoSubscribeOn$SubscribeOnSubscriber.run(MonoSubscribeOn.java:126)
    at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:84)
    at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:37)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
    at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
    at java.base/java.lang.Thread.run(Thread.java:1583)

Also, the usage test was adjusted to avoid failure locally when the container is up for more than a day.

Issues

OPIK-210

[andrescrz]

LGTM.