ci: Replace cancel-previous-runs job with concurrency configuration.

Using ‘github.head_ref || github.run_id’ makes this only cancel
in-progress jobs for pull_request events.

https://docs.github.com/en/actions/using-jobs/using-concurrency

Signed-off-by: Anders Kaseorg <anders@zulip.com>

.github/workflows/cancel-previous-runs.yml

@@ -1,43 +0,0 @@
-name: Cancel previous runs
-on: [push, pull_request]
-
-defaults:
-  run:
-    shell: bash
-
-jobs:
-  cancel:
-    name: Cancel previous runs
-    runs-on: ubuntu-latest
-    timeout-minutes: 3
-
-    # Don't run this job for zulip/zulip pushes since we
-    # want to run those jobs.
-    if: ${{ github.event_name != 'push' || github.event.repository.full_name != 'zulip/zulip' }}
-
-    steps:
-      # We get workflow IDs from GitHub API so we don't have to maintain
-      # a hard-coded list of IDs which need to be updated when a workflow
-      # is added or removed. And, workflow IDs are different for other forks
-      # so this is required.
-      - name: Get workflow IDs.
-        id: workflow_ids
-        continue-on-error: true # Don't fail this job on failure
-        env:
-          # This is in <owner>/<repo> format e.g. zulip/zulip
-          REPOSITORY: ${{ github.repository }}
-        run: |
-          workflow_api_url=https://api.github.com/repos/$REPOSITORY/actions/workflows
-          curl -fL $workflow_api_url -o workflows.json
-
-          script="const {workflows} = require('./workflows'); \
-                  const ids = workflows.map(workflow => workflow.id); \
-                  console.log(ids.join(','));"
-          ids=$(node -e "$script")
-          echo "::set-output name=ids::$ids"
-
-      - uses: styfle/cancel-workflow-action@0.9.0
-        continue-on-error: true # Don't fail this job on failure
-        with:
-          workflow_id: ${{ steps.workflow_ids.outputs.ids }}
-          access_token: ${{ github.token }}

.github/workflows/codeql-analysis.yml

@@ -6,6 +6,10 @@ on:
       - dependabot/** # https://github.com/github/codeql-action/pull/435
   pull_request: {}
 
+concurrency:
+  group: "${{ github.workflow }}-${{ github.head_ref || github.run_id }}"
+  cancel-in-progress: true
+
 jobs:
   CodeQL:
     if: ${{!github.event.repository.private}}

.github/workflows/production-suite.yml

@@ -22,6 +22,10 @@ on:
       - zerver/decorator.py
       - zproject/**
 
+concurrency:
+  group: "${{ github.workflow }}-${{ github.head_ref || github.run_id }}"
+  cancel-in-progress: true
+
 defaults:
   run:
     shell: bash

.github/workflows/zulip-ci.yml

@@ -6,6 +6,10 @@ name: Zulip CI
 
 on: [push, pull_request]
 
+concurrency:
+  group: "${{ github.workflow }}-${{ github.head_ref || github.run_id }}"
+  cancel-in-progress: true
+
 defaults:
   run:
     shell: bash