n1ql and godbc: make sure transports and clients are reused, bodies closed

By code inspection, in at least three places we don't close bodies or create new transports and clients, which will lead to TCP connection leaks.

Potential impact - since we don't specify http transport behaviour, nor that we have done with the body, we are at the mercy of the golang http package as to when connections are closed, which may lead to large tcp connection leaks.