Don't retry query on timeout if we're qname minimizing

When a forwarder fails and we're not in a forward-only mode we go back to regular resolution. When this happens the fetch timer is already running, and we might end up in a situation where we we create a fetch for qname-minimized query and after that the timer is triggered and the query is retried (fctx_try) - which causes relaunching of qname-minimization fetch - and since we already have a qmin fetch for this fctx - assertion failure.

This fix stops the timer when doing qname minimization - qmin fetch internal timer should take care of all the possible timeouts.

Closes #797 (closed)