test: Remove python dead code linter

Primarily I'd like to remove this because it is very imprecise, due to
Python's dynamic nature, giving it a large list of false positives that
need to be listed as exceptions. See for example #16906.

It's also a frequent source of complaints. I'm doubtful of the
usefulness of checking for dead code in a linter in the first place.
Having some dead code in the test framework for a while is not a
disaster.

test/lint/lint-python-dead-code.sh

@@ -1,23 +0,0 @@
-#!/usr/bin/env bash
-#
-# Copyright (c) 2018 The Bitcoin Core developers
-# Distributed under the MIT software license, see the accompanying
-# file COPYING or http://www.opensource.org/licenses/mit-license.php.
-#
-# Find dead Python code.
-
-export LC_ALL=C
-
-if ! command -v vulture > /dev/null; then
-    echo "Skipping Python dead code linting since vulture is not installed. Install by running \"pip3 install vulture\""
-    exit 0
-fi
-
-VULTURE_SUPPRESSIONS=$(dirname "${BASH_SOURCE[0]}")/lint-python-dead-code-whitelist
-if ! vulture \
-    --min-confidence 60 \
-    $(git rev-parse --show-toplevel) \
-    "${VULTURE_SUPPRESSIONS}"; then
-    echo "False positives? Suppressions can be added to ${VULTURE_SUPPRESSIONS}"
-    exit 1
-fi