Add GitHub workflow concurrency controls (hashicorp#22610)

.github/workflows/actionlint.yml

@@ -5,6 +5,11 @@ on:
       - '.github/**'
     types: [opened, synchronize, reopened, ready_for_review]
 
+# cancel existing runs of the same workflow on the same ref
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   actionlint:
     runs-on: ubuntu-latest

.github/workflows/enos-release-testing-oss.yml

@@ -6,6 +6,11 @@ on:
       - enos-release-testing-oss
       - enos-release-testing-oss::*
 
+# cancel existing runs of the same workflow on the same ref
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   product-metadata:
     if: ${{ startsWith(github.event.client_payload.payload.branch, 'release/') }}

.github/workflows/security-scan.yml

@@ -1,5 +1,10 @@
 name: Security Scan
 
+# cancel existing runs of the same workflow on the same ref
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
 on:
   push:
     branches: [main]

.github/workflows/stable-website.yaml

@@ -3,6 +3,11 @@ on:
     types:
       - closed
 
+# cancel existing runs of the same workflow on the same ref
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   stable_website_cherry_pick:
     if: github.event.pull_request.merged && contains(github.event.pull_request.labels.*.name, 'docs-cherrypick')

.github/workflows/test-acc-dockeronly-nightly.yml

@@ -4,6 +4,11 @@ on:
   # Change to nightly cadence once API-credential-requiring tests are added to the jobs
   workflow_dispatch: 
 
+# cancel existing runs of the same workflow on the same ref
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
 # Currently the jobs here are only for acceptance tests that have no dependencies except for Docker
 jobs:
   plugins-database:

.github/workflows/test-ci-bootstrap.yml

@@ -1,5 +1,10 @@
 name: test-ci-bootstrap
 
+# cancel existing runs of the same workflow on the same ref
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
 on:
   workflow_dispatch:
   pull_request:

.github/workflows/test-enos-scenario-ui.yml

@@ -1,6 +1,11 @@
 ---
 name: Vault UI Tests
 
+# cancel existing runs of the same workflow on the same ref
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: true
+
 on:
   workflow_call:
     inputs: