Don't relay Instant Send transaction if 'SPORK_2_INSTANTX' is off
Transaction still relays as instant when 'SPORK_2_INSTANTX' is turned off. The spork is handled in later stages inside 'ProcessMessage' to not lock transactions.
As a result transaction shown as offline for some time in senders wallet and receiver gets transaction notification later.
This can be fixed by just checking instantx spork before relaying it.