m/p/logtree: pipe to t.Log in tests instead of stdout

Change-Id: I12506a0553810d934872aa0dd03478a66ba6e95f
Reviewed-on: https://review.monogon.dev/c/monogon/+/1488
Tested-by: Jenkins CI
Reviewed-by: Leopold Schabel <leo@monogon.tech>
diff --git a/metropolis/pkg/supervisor/supervisor_testhelpers.go b/metropolis/pkg/supervisor/supervisor_testhelpers.go
index 017c9f9..1a72ad8 100644
--- a/metropolis/pkg/supervisor/supervisor_testhelpers.go
+++ b/metropolis/pkg/supervisor/supervisor_testhelpers.go
@@ -57,7 +57,7 @@
 		verbose = true
 	}
 	if verbose {
-		logtree.PipeAllToStderr(t, lt)
+		logtree.PipeAllToTest(t, lt)
 	}
 
 	sup := New(ctx, func(ctx context.Context) error {