Exclude LazyBarrierStrategy by default

[porunov]

LazyBarrierStrategy adds NoOpBarrierStep with the fixed size of 2500 after FlatMapStep. Unless I'm missing something this shouldn't improve JanusGraph query performance anyhow. Should we just exclude this strategy by default to make query.limited-batch-size the only configuration needed to control default added barrier step size?
@rngcntr do you have any opinion about it?

[rngcntr]

In many cases, I can imagine barrier(2500) is not what the user wants, which leads to unwanted performance degradation. In the past, I have often used explicit barrier(1) steps to avoid LazyBarrierStrategy in places where I don't need it. However, I'm not sure there aren't any cases we are missing right now.

[porunov]

I’m not sure either but I couldn’t figure out any use-case when ‘barrier’ step after FlatMapStep improves performance anyhow.
As far as I understand it only degrades performance a little bit with the additional barrier step being processed for no any benefit.
That said, I could be wrong and just miss some none-obvious use-cases.

[porunov]

I have created a topic in TinkerPop Discord channel (here). Unless anyone provides any use-case when LazyBarrierStrategy has benefit when it's used with JanusGraph, I propose to disable this strategy by default.