Merge bitcoin/bitcoin#30723: lint: Speed up and fix flake8 checks

fafdb7df34 lint: Speed up flake8 checks (MarcoFalke)
faf17df7fb lint: Document missing py_lint dependency (MarcoFalke)
faebeb828f lint: Remove python whitespace and shadowing lint rules (MarcoFalke)
7777047835 lint: Remove python lint rules that are SyntaxError (MarcoFalke)
faaf3e53f0 test: [refactor] Fix F841 flake8 (MarcoFalke)
444421db69 test: [refactor] Fix E714 pycodestyle (MarcoFalke)

Pull request description:

  The checks have many issues:

  * Some checks that could in theory hide bugs are not applied -> Fix them and apply them going forward
  * Some checks are redundant Python 2 checks, or of low value -> Remove them
  * The checks are slow -> Speed them up from ~10 seconds to about ~20 milliseconds

ACKs for top commit:
  davidgumberg:
    review and tested reACK fafdb7df34
  kevkevinpal:
    ACK [fafdb7d](fafdb7df34)
  achow101:
    ACK fafdb7df34

Tree-SHA512: a0488b722cfaf7071bd6848cd3be002e0b6c38af80d8b5cbb08613c0b174ef63277289f960db8ac31adb09fe563a4973203b8fb10b83cbcfdc6f0ef39bd04410

test/functional/test_framework/blocktools.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# Copyright (c) 2015-2022 The Bitcoin Core developers
+# Copyright (c) 2015-present The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Utilities for manipulating blocks and transactions."""
@@ -74,7 +74,7 @@ def create_block(hashprev=None, coinbase=None, ntime=None, *, version=None, tmpl
     block.nVersion = version or tmpl.get('version') or VERSIONBITS_LAST_OLD_BLOCK_VERSION
     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:
+    if tmpl and tmpl.get('bits') is not None:
         block.nBits = struct.unpack('>I', bytes.fromhex(tmpl['bits']))[0]
     else:
         block.nBits = 0x207fffff  # difficulty retargeting is disabled in REGTEST chainparams