fa4c16d qa: Add getrawtransaction in_active_chain=False test (MarcoFalke)
Pull request description:
#10275 accidentally forgot to add a test for `in_active_chain==False`. This adds a test and also removes the special casing of `blockhash.IsNull()`, which makes no sense imo.
Tree-SHA512: 6c51295820b3dcd53b0b48020ab2b8c8f5864cd5061ddab2b35d35d643eb3e60ef95ff20c06c985a2e47f7080e82f27f3e00ee61c85dce627776d5ea6febee8f
Backport of Core PR 11838
https://github.com/bitcoin/bitcoin/pull/11838/files
Completes T593