cmd/govulncheck: disable cmdtest logging

Turn off the logging that the cmdtest package does, which clutters
test output.

Change-Id: I0a03b0166fdc78e355cd4fe9a4312200d41c92b4
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/399118
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Zvonimir Pavlinovic <zpavlinovic@google.com>
diff --git a/cmd/govulncheck/main_test.go b/cmd/govulncheck/main_test.go
index 26ba4fc..fb42539 100644
--- a/cmd/govulncheck/main_test.go
+++ b/cmd/govulncheck/main_test.go
@@ -33,6 +33,7 @@
 	if err != nil {
 		t.Fatal(err)
 	}
+	ts.DisableLogging = true
 	// Define a command that lets us cd into a module directory.
 	// The modules for these tests live under testdata/modules.
 	ts.Commands["cdmodule"] = func(args []string, inputFile string) ([]byte, error) {