Extend presubmit to covert test and request (#1846)

Fix the casing *and* fix use of context as we were still referencing
the non-std lib context - no wondering how this could have worked...

test/plugin_test.go

@@ -17,7 +17,7 @@ func benchmarkLookupBalanceRewriteCache(b *testing.B) {
 	t := new(testing.T)
 	name, rm, err := test.TempFile(".", exampleOrg)
 	if err != nil {
-		t.Fatalf("failed to create zone: %s", err)
+		t.Fatalf("Failed to create zone: %s", err)
 	}
 	defer rm()