Merge bitcoin/bitcoin#22429: test: refactor: fix segwit terminology (s/witness_program/witness_script/)

8a2b58db9e test: fix segwit terminology (s/witness_program/witness_script/) (Sebastian Falbesoner)

Pull request description:

  This PR fixes wrong uses of the term "witness program", which according to [BIP141](https://github.com/bitcoin/bips/blob/master/bip-0141.mediawiki#Witness_program)  is defined as follows:
  > A scriptPubKey (or redeemScript as defined in BIP16/P2SH) that consists of a 1-byte push opcode (for 0 to 16) followed by a data push between 2 and 40 bytes gets a new special meaning. The value of the first push is called the "version byte". **The following byte vector pushed is called the "witness program".**

  In most cases where "witness program" is used in tests (concerns comments, variable names and in one instance even a function name) what we really want to denote is the "witness script". Thanks to [MarcoFalke for pointing this out in a review comment](https://github.com/bitcoin/bitcoin/pull/22363#discussion_r666794261)!

  Some historical background: At the time when the P2P segwit tests were first introduced (commit 330b0f31ee, PR #8149), the term "witness program" was not used consistently in BIP141: https://bitcoin.stackexchange.com/questions/46451/what-is-the-precise-definition-of-witness-program
  This was fixed in PR https://github.com/bitcoin/bips/pull/416 later.

  So in some way, this PR can be seen as a very late follow-up to the BIP141 fix that also reflects these changes in the tests.

ACKs for top commit:
  josibake:
    tACK 8a2b58db9e

Tree-SHA512: f36bb9e53d1b54b86bfa87ec12f33e3ebca64b5f59d97e9662fe35ba12c25e1c9a4f93a5425d0eaa3879dce9e50368d345555b927bfab76945511f873396892b

test/functional/test_framework/blocktools.py

@@ -214,8 +214,8 @@ def witness_script(use_p2wsh, pubkey):
         pkscript = key_to_p2wpkh_script(pubkey)
     else:
         # 1-of-1 multisig
-        witness_program = CScript([OP_1, hex_str_to_bytes(pubkey), OP_1, OP_CHECKMULTISIG])
-        pkscript = script_to_p2wsh_script(witness_program)
+        witness_script = CScript([OP_1, hex_str_to_bytes(pubkey), OP_1, OP_CHECKMULTISIG])
+        pkscript = script_to_p2wsh_script(witness_script)
     return pkscript.hex()
 
 def create_witness_tx(node, use_p2wsh, utxo, pubkey, encode_p2sh, amount):