Diff testing may fail with OOME while reading blocks from disk

Sample stack trace:

```
Error: Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.base/java.io.InputStream.readNBytes(InputStream.java:408)
at java.base/java.io.InputStream.readAllBytes(InputStream.java:349)
at com.hedera.statevalidation.blockstream.BlockStreamUtils.blockFrom(BlockStreamUtils.java:173)
at com.hedera.statevalidation.blockstream.BlockStreamUtils$$Lambda/0x00007f3cc03e5728.apply(Unknown Source)
at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197)
at java.base/java.util.AbstractList$RandomAccessSpliterator.forEachRemaining(AbstractList.java:722)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:575)
at java.base/java.util.stream.AbstractPipeline.evaluateToArrayNode(AbstractPipeline.java:260)
at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:616)
at java.base/java.util.stream.ReferencePipeline.toArray(ReferencePipeline.java:622)
at java.base/java.util.stream.ReferencePipeline.toList(ReferencePipeline.java:627)
at com.hedera.statevalidation.blockstream.BlockStreamUtils.readBlocks(BlockStreamUtils.java:156)
at com.hedera.statevalidation.blockstream.BlockStreamRecoveryWorkflow.applyBlocks(BlockStreamRecoveryWorkflow.java:64)
at com.hedera.statevalidation.ApplyBlocksCommand.call(ApplyBlocksCommand.java:72)
at com.hedera.statevalidation.ApplyBlocksCommand.call(ApplyBlocksCommand.java:14)
at picocli.CommandLine.executeUserObject(CommandLine.java:2031)
at picocli.CommandLine.access$1500(CommandLine.java:148)
at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2469)
at picocli.CommandLine$RunLast.handle(CommandLine.java:2461)
at picocli.CommandLine$RunLast.handle(CommandLine.java:2423)
at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2277)
at picocli.CommandLine$RunLast.execute(CommandLine.java:2425)
at picocli.CommandLine.execute(CommandLine.java:2174)
at com.hedera.statevalidation.StateOperatorCommand.main(StateOperatorCommand.java:36)
```