plugin/forward: remove dynamic read timeout (#2319)

* plugin/forward: remove dynamic read timeout

We care about an upstream being there, so we still have a dynamic dial
time out (by way higher then 200ms) of 1s; this should be fairly stable
for an upstream. The read timeout if more variable because of cached and
non cached responses. As such remove his logic entirely.

Drop to 2s read timeout.

Fixes #2306

Signed-off-by: Miek Gieben <miek@miek.nl>

plugin/forward/proxy.go

@@ -11,8 +11,7 @@ import (
 
 // Proxy defines an upstream host.
 type Proxy struct {
-	avgRtt int64
-	fails  uint32
+	fails uint32
 
 	addr string
 
@@ -32,7 +31,6 @@ func NewProxy(addr, trans string) *Proxy {
 		fails:     0,
 		probe:     up.New(),
 		transport: newTransport(addr),
-		avgRtt:    int64(maxTimeout / 2),
 	}
 	p.health = NewHealthChecker(trans)
 	runtime.SetFinalizer(p, (*Proxy).finalizer)