Merge bitcoin/bitcoin#22619: test: refactor: use consistent bytes <-> hex-string conversion in functional test framework

5a1bef60a0 test: refactor: remove binascii from test_framework (Zero-1729)

Pull request description:

  This PR continues the work started in PR #22593, regarding using the `bytes` built-in module. In this PR specifically, instances of `binascii`'s methods `hexlify`, `unhexlify`,  and `a2b_hex` have been replaced with the build-in `bytes` module's `hex` and `fromhex` methods where appropriate to make bytes <-> hex-string conversions consistent across the functional test files and test_framework.

  Additionally, certain changes made are based on the following assumption:

  ```
  bytes.hex(data) == binascii.hexlify(data).decode()
  bytes.hex(data).encode() == binascii.hexlify(data)
  ```

  Ran the functional tests to ensure behaviour is still consistent and changes didn't break existing tests.

  closes #22605

ACKs for top commit:
  theStack:
    Code-review ACK 5a1bef60a0 🔢

Tree-SHA512: 8f28076cf0580a0d02a156f3e1e94c9badd3d41c3fbdfb2b87cd8a761dde2c94faa5f4c448d6747b1ccc9111c3ef1a1d7b42a11c806b241fa0410b7529e2445f

test/functional/test_framework/blocktools.py

@@ -4,7 +4,6 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Utilities for manipulating blocks and transactions."""
 
-from binascii import a2b_hex
 import struct
 import time
 import unittest
@@ -74,7 +73,7 @@ def create_block(hashprev=None, coinbase=None, ntime=None, *, version=None, tmpl
     block.nTime = ntime or tmpl.get('curtime') or int(time.time() + 600)
     block.hashPrevBlock = hashprev or int(tmpl['previousblockhash'], 0x10)
     if tmpl and not tmpl.get('bits') is None:
-        block.nBits = struct.unpack('>I', a2b_hex(tmpl['bits']))[0]
+        block.nBits = struct.unpack('>I', bytes.fromhex(tmpl['bits']))[0]
     else:
         block.nBits = 0x207fffff  # difficulty retargeting is disabled in REGTEST chainparams
     if coinbase is None: