When the relay to measure is an exit, check `bwscanner_cc` and `FlowCtrl` before using it as an exit

Working on analysis#36 (closed) made me realize that we still had the line https://gitlab.torproject.org/tpo/network-health/sbws/-/blob/m15/sbws/core/scanner.py#L401 that use the relay to measure as an exit without checking bwscanner_cc or FlowCtrl, even if we added 037dd9c3.

That was causing that sometimes a CC circuit was built when bwscanner_cc wasn't equal or greater than 1 or the other way around.