NIFI-5952 Refactor RAW S2S from nio to socket

[ijokarumawak]

NOTE This PR is based on NIFI-5820's PR branch because this fix is required after NIFI-5820 is merged, in order to support Site-to-Site with RAW transport protocol running on Java 11.

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[markap14]

Thanks for the update @ijokarumawak . I don't love that we are going from NIO to the "regular IO" based API, but I agree with your assessment that it's a fairly straight-forward change that will allow us to use site-to-site with Java 11. I did test this against both Java 8 and Java 11 and things seemed to be working well. +1 Have merged to master.