Improve fake_v5_transaction_with_orchard_actions_has_inputs_and_outputs test

[oxarbitrage]

In #2398 we extended the fake_v5_transaction_with_orchard_actions_has_inputs_and_outputs unit test for new consensus rules.

In this test we are calling insert_fake_orchard_shielded_data() multiple times which i think it can be avoided.

This is a very low priority clean up task.

[oxarbitrage]

In the worst case this is a minor performance issue inside a specific test. Not very important at the moment.

[upbqdn]

I accidentally addressed this by fixing something else. I'll open a PR soon.