tests: add worker count to class description
While running test:
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NAT44ED Test Case
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==>
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NAT44ED Test Case [main thread only]
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NAT44ED Test Case [1 worker thread]
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NAT44ED Test Case [4 worker threads]
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Type: improvement
Signed-off-by: Klement Sekera <ksekera@cisco.com>
Change-Id: I61904b411ff1b58700564698079dc4c07cea5c5e