mw/file: rename to BenchmarkFileLookup (#741)

In grafana we miss the context of where this is called, make the name
more descriptive.

Also test the GH webhook.

test/proxy_test.go

@@ -100,7 +100,7 @@ func TestLookupDnsWithForcedTcp(t *testing.T) {
 	}
 }
 
-func BenchmarkLookupProxy(b *testing.B) {
+func BenchmarkProxyLookup(b *testing.B) {
 	t := new(testing.T)
 	name, rm, err := test.TempFile(".", exampleOrg)
 	if err != nil {