[CONNECTOR-633] Increased incoming message limit and event loop fixes

[ashishshinde]

• Increased the incoming payload size to 128MB
• onError and onNext were at times called from non-event loop threads. Scheduled these calls on event loop to ensure thread safety.
• minor formatting change
• allowed sync calls from benchmarks
• minor formatting fixes

[BrianNichols]

Accepted the majority of changes.