ci: Add pyutils container

Currently, our jobs which only want to run a little bit of python -
python-test and the LAVA jobs - pull the entire x86_64-build image,
which is both massive, and massively unnecessary.

Create a separate image which only carries what we need to run our
Python tests and utilities, and switch python-test to using that.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31151>

.gitlab-ci/prepare-artifacts-python.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC2038 # TODO: rewrite the find
+# shellcheck disable=SC2086 # we want word splitting
+
+section_switch prepare-artifacts "artifacts: prepare"
+
+set -e
+set -o xtrace
+
+mkdir -p artifacts/
+
+# Test runs don't pull down the git tree, so put the dEQP helper
+# script and associated bits there.
+echo "$(cat VERSION) (git-$(git rev-parse HEAD | cut -b -10))" > artifacts/VERSION
+cp -Rp .gitlab-ci/report-flakes.py artifacts/
+cp -Rp .gitlab-ci/setup-test-env.sh artifacts/
+cp -Rp .gitlab-ci/common artifacts/ci-common
+cp -Rp .gitlab-ci/b2c artifacts/
+cp -Rp .gitlab-ci/bare-metal artifacts/
+cp -Rp .gitlab-ci/lava artifacts/
+cp -Rp .gitlab-ci/bin/*_logger.py artifacts/
+
+mapfile -t duplicate_files < <(
+  find src/ -path '*/ci/*' \
+    \( \
+      -name '*.txt' \
+      -o -name '*.toml' \
+      -o -name '*traces*.yml' \
+    \) \
+    -exec basename -a {} + | sort | uniq -d
+)
+if [ ${#duplicate_files[@]} -gt 0 ]; then
+  echo 'Several files with the same name in various ci/ folders:'
+  printf -- '  %s\n' "${duplicate_files[@]}"
+  exit 1
+fi
+
+find src/ -path '*/ci/*' \
+  \( \
+    -name '*.txt' \
+    -o -name '*.toml' \
+    -o -name '*traces*.yml' \
+  \) \
+  -exec cp -p {} artifacts/ \;
+cp -Rp .gitlab-ci/*.txt artifacts/
+
+if [ -n "$S3_ARTIFACT_NAME" ]; then
+    # Pass needed files to the test stage
+    S3_ARTIFACT_TAR="$S3_ARTIFACT_NAME.tar.zst"
+    tar cv artifacts/ | zstd -o "${S3_ARTIFACT_TAR}"
+    ci-fairy s3cp --token-file "${S3_JWT_FILE}" "${S3_ARTIFACT_TAR}" "https://${PIPELINE_ARTIFACTS_BASE}/${S3_ARTIFACT_TAR}"
+    rm "${S3_ARTIFACT_TAR}"
+fi
+
+section_end prepare-artifacts