apps.mellanox: make per-queue counter creation configurable
apps.mellanox: make per-queue counter creation configurable

Currenty, we create HCAs per stats request, and create indepedent
stats requests for each per-queue counter set.

HCAs are a limited resource, and many-queue configurations might run out
of HCAs.

As a workaround, allow counter set creation to be disabled per-queue.

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