ci: enable gocognit (#9359)

And, bring the server under 300:

* Removed the undocumented "disable" STUN address in favor of the
--disable-direct flag.

cli/server_test.go

@@ -1496,31 +1496,6 @@ func TestServer(t *testing.T) {
 			w.RequireSuccess()
 		})
 	})
-	t.Run("DisableDERP", func(t *testing.T) {
-		t.Parallel()
-
-		// Make sure that $CODER_DERP_SERVER_STUN_ADDRESSES can be set to
-		// disable STUN.
-
-		inv, cfg := clitest.New(t,
-			"server",
-			"--in-memory",
-			"--http-address", ":0",
-			"--access-url", "https://example.com",
-		)
-		inv.Environ.Set("CODER_DERP_SERVER_STUN_ADDRESSES", "disable")
-		ptytest.New(t).Attach(inv)
-		clitest.Start(t, inv)
-		gotURL := waitAccessURL(t, cfg)
-		client := codersdk.New(gotURL)
-
-		ctx := testutil.Context(t, testutil.WaitMedium)
-		_ = coderdtest.CreateFirstUser(t, client)
-		gotConfig, err := client.DeploymentConfig(ctx)
-		require.NoError(t, err)
-
-		require.Len(t, gotConfig.Values.DERP.Server.STUNAddresses, 0)
-	})
 }
 
 func TestServer_Production(t *testing.T) {