Merge bitcoin/bitcoin#31948: ci: [lint] Use Cirrus dockerfile cache

fa3b442 ci: Use Cirrus dockerfile cache (MarcoFalke)

Pull request description:

  The lint task is problematic, because:

  * It doesn't check modifications to `ci/lint_imagefile`
  * It calls a separate script that installs packages on every run (taking time)
  * It uses `*_cache` instructions to cache some installed parts, but not all

  Fix all issues by using `ci/lint_imagefile` (https://cirrus-ci.org/guide/docker-builder-vm/#dockerfile-as-a-ci-environment)

ACKs for top commit:
  willcl-ark:
    ACK fa3b442

Tree-SHA512: 243d78219639b83721d4e5cb32d16e5c208a61c919d04646279be5825ba92d97c490b5d4d28ea103eb820b1a259904574cb3e32eaca3f11c3031810e3d87ff4a

Author: fanquake

.cirrus.yml

@@ -96,21 +96,15 @@ task:
   name: 'lint'
   << : *BASE_TEMPLATE
   container:
-    image: debian:bookworm
+    dockerfile: ci/lint_imagefile
     cpu: 1
     memory: 1G
   # For faster CI feedback, immediately schedule the linters
   << : *CREDITS_TEMPLATE
-  test_runner_cache:
-    folder: "/lint_test_runner"
-    fingerprint_script: echo $CIRRUS_TASK_NAME $(git rev-parse HEAD:test/lint/test_runner)
-  python_cache:
-    folder: "/python_build"
-    fingerprint_script: cat .python-version /etc/os-release
   unshallow_script:
     - git fetch --unshallow --no-tags
   lint_script:
-    - ./ci/lint_run_all.sh
+    - ./ci/lint_run.sh
 
 task:
   name: 'tidy'

ci/lint_run.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+export LC_ALL=C.UTF-8
+set -o errexit -o pipefail -o xtrace
+
+# Only used in .cirrus.yml. Refer to test/lint/README.md on how to run locally.
+export PATH="/python_build/bin:${PATH}"
+export LINT_RUNNER_PATH="/lint_test_runner"
+./ci/lint/06_script.sh

ci/lint_run_all.sh

@@ -6,7 +6,8 @@
 
 export LC_ALL=C.UTF-8
 
-# Only used in .cirrus.yml. Refer to test/lint/README.md on how to run locally.
+# Only used in .cirrus.yml for stale re-runs of old pull request tasks. This
+# file can be removed in September 2025.
 
 cp "./ci/retry/retry" "/ci_retry"
 cp "./.python-version" "/.python-version"