MINOR: stream: Simplify retries counter calculation

MINOR: stream: Simplify retries counter calculation

The conn_retries counter was set to the max value and decremented at each
connection retry. Thus the counter reflected the number of retries left and
not the real number of retries. All calculations of redispatch or reporting
of number of retries experienced were made using subtracts from the
configured retries, which was complicated and didn't bring any benefit.

Now, this counter is set to 0 and incremented at each retry. We know we've
reached the maximum allowed connection retries by comparing it to the
configured value. In all other cases, we directly use the counter.

This patch should address the feature request #1608.