Revert "osbase/logtree: add WithBacklogOrder"

This reverts commit 3553b240af181f5eba87ffd2af9323fa054e1967.

Reason for revert: We don't have any consumer for this API as WithStartPosition will be sufficient.

Change-Id: I6553a99d16b6f11160df31074f44431b5a6592ed
Reviewed-on: https://review.monogon.dev/c/monogon/+/4464
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/osbase/logtree/journal_test.go b/osbase/logtree/journal_test.go
index 944e4fb..826f2e7 100644
--- a/osbase/logtree/journal_test.go
+++ b/osbase/logtree/journal_test.go
@@ -38,7 +38,7 @@
 		t.Fatalf("wanted %d entries, got %d", want, got)
 	}
 	for i, entry := range entries {
-		want := fmt.Sprintf("test %d", 9000-1-i)
+		want := fmt.Sprintf("test %d", (9000-defaultDNQuota)+i)
 		got := strings.Join(entry.leveled.messages, "\n")
 		if want != got {
 			t.Fatalf("wanted entry %q, got %q", want, got)