tools: Reimplement CI failure script without using CircleCI endpoint.

Using curl to POST to the CircleCI workflow endpoint on CZO:

- Doesn't work on zulip/zulip@main (CZO runs a revert)
- Sets a bad example for other orgs
- Robs us of an opportunity to dogfood our own zulip/github-actions-zulip

Refactor the Actions workflows in this repo to report failure states
using the Zulip Action, and reimplement the related helper scripts in
Python, since they'd previously mostly shelled out to Python anyway.

tools/ci/generate-failure-message

@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+
+import os
+
+
+def get_build_url_from_environment() -> str:
+    server = os.environ["GITHUB_SERVER_URL"]
+    repo = os.environ["GITHUB_REPOSITORY"]
+    run_id = os.environ["GITHUB_RUN_ID"]
+    return f"{server}/{repo}/actions/runs/{run_id}"
+
+
+if __name__ == "__main__":
+    branch = os.environ.get("GITHUB_REF", "unknown branch").split("/")[-1]
+    topic = f"{branch} failing"
+    build_url = get_build_url_from_environment()
+    github_actor = os.environ.get("GITHUB_ACTOR", "unknown user")
+    content = f"[Build]({build_url}) triggered by {github_actor} on branch `{branch}` has failed."
+
+    # Output in the key-value pair format GitHub Actions outputs are expected
+    # to be in.
+    print(f"topic={topic}\ncontent={content}")

tools/ci/production-build

@@ -39,7 +39,7 @@ cp -a \
     tools/ci/production-upgrade \
     tools/ci/production-pgroonga \
     tools/ci/production-upgrade-pg \
-    tools/ci/send-failure-message \
+    tools/ci/generate-failure-message \
     package.json yarn.lock \
     /tmp/production-build
 

tools/ci/send-failure-message

@@ -1,12 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-set -x
-
-if [[ "$ZULIP_BOT_KEY" != "" && "$GITHUB_REPOSITORY" == "zulip/zulip" ]]; then
-    BRANCH="$(python3 -c 'import sys; print(sys.argv[1].split("/")[-1])' "$GITHUB_REF")"
-    URI_ESCAPED_TOPIC="$(python3 -c 'import sys; import urllib.parse; print(urllib.parse.quote(sys.argv[1]))' "$BRANCH failing")"
-    curl -fL -H "Content-Type: application/json" \
-        -X POST -i 'https://chat.zulip.org/api/v1/external/circleci?api_key='"$ZULIP_BOT_KEY"'&stream=automated%20testing&topic='"$URI_ESCAPED_TOPIC" \
-        -d '{"payload": { "branch": "'"$BRANCH"'", "reponame": "'"$GITHUB_REPOSITORY"'", "status": "failed", "build_url": "'"$GITHUB_SERVER_URL/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID"'", "username": "'"$GITHUB_ACTOR"'"}}'
-fi