Ticket 40724: Add metrics for CC circuit counts

src/core/or/circuitlist.c

src/core/or/circuitlist.h

src/core/or/congestion_control_common.c

src/core/or/congestion_control_common.h

src/core/or/congestion_control_vegas.c

src/core/or/congestion_control_vegas.h

src/feature/relay/relay_metrics.c