RecordIOFramingSpec "should parse a series of records" is flaky

Failing in main branch. Also in some PRs.

```
[info] RecordIOFramingSpec:
[info] RecordIO framing
[info] - should parse a series of records *** FAILED *** (1 second, 4 milliseconds)
[info] A timeout occurred waiting for a future to complete. Waited 600 milliseconds. (RecordIOFramingSpec.scala:72)
[info] org.scalatest.concurrent.ScalaFutures$$anon$1$$anon$2:
[info] at org.scalatest.concurrent.ScalaFutures$$anon$1.futureValueImpl(ScalaFutures.scala:339)
[info] at org.scalatest.concurrent.Futures$FutureConcept.futureValue(Futures.scala:476)
[info] at org.scalatest.concurrent.Futures$FutureConcept.futureValue$(Futures.scala:475)
[info] at org.scalatest.concurrent.ScalaFutures$$anon$1.futureValue(ScalaFutures.scala:281)
[info] at docs.scaladsl.RecordIOFramingSpec.$anonfun$new$1(RecordIOFramingSpec.scala:72)
[info] at org.scalatest.OutcomeOf.outcomeOf(OutcomeOf.scala:85)
[info] at org.scalatest.OutcomeOf.outcomeOf$(OutcomeOf.scala:83)
[info] at org.scalatest.OutcomeOf$.outcomeOf(OutcomeOf.scala:104)
[info] at org.scalatest.Transformer.apply(Transformer.scala:22)
[info] at org.scalatest.Transformer.apply(Transformer.scala:20)
[info] at org.scalatest.flatspec.AnyFlatSpecLike$$anon$5.apply(AnyFlatSpecLike.scala:1832)
[info] at org.apache.pekko.stream.connectors.testkit.scaladsl.LogCapturing.withFixture(LogCapturing.scala:70)
[info] at org.apache.pekko.stream.connectors.testkit.scaladsl.LogCapturing.withFixture$(LogCapturing.scala:66)
[info] at docs.scaladsl.RecordIOFramingSpec.withFixture(RecordIOFramingSpec.scala:35)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.invokeWithFixture$1(AnyFlatSpecLike.scala:1830)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$runTest$1(AnyFlatSpecLike.scala:1842)
[info] at org.scalatest.SuperEngine.runTestImpl(Engine.scala:306)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.runTest(AnyFlatSpecLike.scala:1842)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.runTest$(AnyFlatSpecLike.scala:1824)
[info] at docs.scaladsl.RecordIOFramingSpec.runTest(RecordIOFramingSpec.scala:35)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$runTests$1(AnyFlatSpecLike.scala:1900)
[info] at org.scalatest.SuperEngine.$anonfun$runTestsInBranch$1(Engine.scala:413)
[info] at scala.collection.immutable.List.foreach(List.scala:431)
[info] at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
[info] at org.scalatest.SuperEngine.runTestsInBranch(Engine.scala:390)
[info] at org.scalatest.SuperEngine.$anonfun$runTestsInBranch$1(Engine.scala:427)
[info] at scala.collection.immutable.List.foreach(List.scala:431)
[info] at org.scalatest.SuperEngine.traverseSubNodes$1(Engine.scala:401)
[info] at org.scalatest.SuperEngine.runTestsInBranch(Engine.scala:396)
[info] at org.scalatest.SuperEngine.runTestsImpl(Engine.scala:475)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.runTests(AnyFlatSpecLike.scala:1900)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.runTests$(AnyFlatSpecLike.scala:18[99](https://github.com/apache/pekko-connectors/actions/runs/11090678254/job/30813328924#step:5:100))
[info] at docs.scaladsl.RecordIOFramingSpec.runTests(RecordIOFramingSpec.scala:35)
[info] at org.scalatest.Suite.run(Suite.scala:1114)
[info] at org.scalatest.Suite.run$(Suite.scala:1096)
[info] at docs.scaladsl.RecordIOFramingSpec.org$scalatest$flatspec$AnyFlatSpecLike$$super$run(RecordIOFramingSpec.scala:35)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.$anonfun$run$1(AnyFlatSpecLike.scala:1945)
[info] at org.scalatest.SuperEngine.runImpl(Engine.scala:535)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.run(AnyFlatSpecLike.scala:1945)
[info] at org.scalatest.flatspec.AnyFlatSpecLike.run$(AnyFlatSpecLike.scala:1943)
[info] at docs.scaladsl.RecordIOFramingSpec.org$scalatest$BeforeAndAfterAll$$super$run(RecordIOFramingSpec.scala:35)
[info] at org.scalatest.BeforeAndAfterAll.liftedTree1$1(BeforeAndAfterAll.scala:213)
[info] at org.scalatest.BeforeAndAfterAll.run(BeforeAndAfterAll.scala:210)
[info] at org.scalatest.BeforeAndAfterAll.run$(BeforeAndAfterAll.scala:208)
[info] at docs.scaladsl.RecordIOFramingSpec.run(RecordIOFramingSpec.scala:35)
[info] at org.scalatest.tools.Framework.org$scalatest$tools$Framework$$runSuite(Framework.scala:321)
[info] at org.scalatest.tools.Framework$ScalaTestTask.execute(Framework.scala:517)
[info] at sbt.TestRunner.runTest$1(TestFramework.scala:153)
[info] at sbt.TestRunner.run(TestFramework.scala:168)
[info] at sbt.TestFramework$$anon$3$$anonfun$$lessinit$greater$1.$anonfun$apply$1(TestFramework.scala:336)
[info] at sbt.TestFramework$.sbt$TestFramework$$withContextLoader(TestFramework.scala:296)
[info] at sbt.TestFramework$$anon$3$$anonfun$$lessinit$greater$1.apply(TestFramework.scala:336)
[info] at sbt.TestFramework$$anon$3$$anonfun$$lessinit$greater$1.apply(TestFramework.scala:336)
[info] at sbt.TestFunction.apply(TestFramework.scala:348)
[info] at sbt.Tests$.processRunnable$1(Tests.scala:475)
[info] at sbt.Tests$.$anonfun$makeSerial$1(Tests.scala:481)
[info] at sbt.std.Transform$$anon$3.$anonfun$apply$2(Transform.scala:47)
[info] at sbt.std.Transform$$anon$4.work(Transform.scala:69)
[info] at sbt.Execute.$anonfun$submit$2(Execute.scala:283)
[info] at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:24)
[info] at sbt.Execute.work(Execute.scala:292)
[info] at sbt.Execute.$anonfun$submit$1(Execute.scala:283)
[info] at sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[info] at sbt.CompletionService$$anon$2.call(CompletionService.scala:65)
[info] at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[info] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
[info] at java.util.concurrent.FutureTask.run(FutureTask.java:266)
[info] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:[114](https://github.com/apache/pekko-connectors/actions/runs/11090678254/job/30813328924#step:5:115)9)
[info] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
[info] at java.lang.Thread.run(Thread.java:750)
```

Start with RecordIOFramingSpec.scala, especially the test at line 72 for "should parse a series of records," and reproduce the 600-millisecond timeout. Read the surrounding fixture and test setup to determine why the test sometimes fails, then verify the fix by running this spec repeatedly and confirming the test completes reliably.

Written by the indexing model from the issue text.