Fixes test: The comment is obsolete (because we're not using the reso…

…urceWaitTimeout anymore) and just adds confusion because we don't need to wait in this test:

0. The mentioned test method #testRequirementLowerBoundIncreaseBeyondCurrentParallelismAttemptsImmediateRescale does not exist (#testRequirementLowerBoundIncreaseBeyondCurrentParallelismKeepsJobRunning is most likely meant)
1. the startJobWithSlotsMatchingParallelism will be executed in the main thread and, therefore, finishes before updateJobResourceRequirements is triggered (which also runs in the main thread)
2. Running both calls in the main thread ensures sequential execution of the commands with the scheduler being in WaitingForResources state when calling updateJobResourceRequirements

flink-runtime/src/test/java/org/apache/flink/runtime/scheduler/adaptive/AdaptiveSchedulerTest.java

@@ -1263,14 +1263,6 @@ void testRequirementLowerBoundDecreaseAfterResourceScarcityBelowAvailableSlots()
         startJobWithSlotsMatchingParallelism(
                 scheduler, declarativeSlotPool, taskManagerGateway, availableSlots);
 
-        // at this point we'd ideally check that the job is stuck in WaitingForResources, but we
-        // can't differentiate between waiting due to the minimum requirements not being fulfilled
-        // and the resource timeout not being elapsed
-        // We just continue here, as the following tests validate that the lower bound can prevent
-        // a job from running:
-        // - #testInitialRequirementLowerBoundBeyondAvailableSlotsCausesImmediateFailure()
-        // - #testRequirementLowerBoundIncreaseBeyondCurrentParallelismAttemptsImmediateRescale()
-
         // unlock job by decreasing the parallelism
         JobResourceRequirements newJobResourceRequirements =
                 createRequirementsWithLowerAndUpperParallelism(availableSlots, PARALLELISM);