NIFI-8039 Adding properties to ListenTCP in order to allow refine behaviour under higher load; Refining thread pool for better scalability

[simonbence]

NIFI-8039

Current implementation of ListenTCP might consume high amount of resources at processor initialisation and keeps them acquired regardless the load. My proposal contains changes in order to mitigate this. These includes:

• Replacement of the fixed thread pool into a more scalable one
• The opportunity to create byte buffers ad hod instead of pooling high number of instances

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Enables X functionality; fixes bug NIFI-YYYY.

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[turcsanyip]

+1 LGTM

Merging to main.