routing+itest: fix route blinding path selection bug

Here we fix a bug which would not include the selected incoming blinded
path chain from being included in the selected path set if it meets the
minimum length requirement. The appropriate unit test and itest is
updated to demonstrate the fix.

routing/pathfind_test.go

@@ -3941,9 +3941,11 @@ func TestFindBlindedPaths(t *testing.T) {
 	require.NoError(t, err)
 
 	// We expect the following paths:
+	//	- B, D
 	//	- F, B, D
 	// 	- E, B, D
 	assertPaths(paths, []string{
+		"bob,dave",
 		"frank,bob,dave",
 		"eve,bob,dave",
 	})