Merge #20189: test: Switch to BIP341's suggested scheme for outputs without script

812baaa Switch to BIP341's suggested scheme for outputs without script (Pieter Wuille)

Pull request description:

  BIP341 suggests using Hash<sub>TapTweak</sub>(pubkey) to derive the tweak in case of key-only outputs. The functional test framework currently uses Hash<sub>TapTweak</sub>(pubkey || 0x00...00) instead. Change this.

  There is no technical reason to prefer one over the other, but in case someone looks at it for inspiration, it's better to be consistent with the BIP.

ACKs for top commit:
  laanwj:
    ACK 812baaa
  instagibbs:
    ACK bitcoin/bitcoin@812baaa

Tree-SHA512: 02576c38776ec786255f49d7edecdb1ed8a9dcf0f547d58c23099588b4c3296edf279b103a6eb80e0f07d3c5ee9743f67d152f5244fd63adc6613b004f6969ed

Author: MarcoFalke

test/functional/test_framework/script.py

@@ -787,7 +787,7 @@ def TaprootSignatureHash(txTo, spent_utxos, hash_type, input_index = 0, scriptpa
 
 def taproot_tree_helper(scripts):
     if len(scripts) == 0:
-        return ([], bytes(0 for _ in range(32)))
+        return ([], bytes())
     if len(scripts) == 1:
         # One entry: treat as a leaf
         script = scripts[0]