Use cancel-in-progress instead of styfle/cancel-workflow-action.

Compare google/guava#8542.

Aside from the reasons listed there, I wonder if this would have avoided a flaky(?) failure that I saw today on #1441:

```
Run styfle/cancel-workflow-action@d07a454
  with:
    access_token: ***
    ignore_sha: false
    all_but_latest: false
    force_cancel: false
{
  eventName: 'pull_request',
  sha: 'ca5f660437c7f1489d511540cf8c6d047ea0edcf',
  headSha: 'a160145b17ff487adfa4519b087472e3d328088d',
  branch: 'zizdep',
  owner: 'google',
  repo: 'google-java-format',
  GITHUB_RUN_ID: '31412633123'
}
Found token: yes
Error: self-signed certificate; if the root CA is installed locally, try running Node.js with --use-system-ca
```

Author: cpovirk

.github/workflows/ci.yml

@@ -25,6 +25,11 @@ on:
 permissions:
   contents: read
 
+# Cancel in-progress runs for pull requests, but not for master branch pushes
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 jobs:
   test-OpenJDK:
     name: "JDK ${{ matrix.java }} on ${{ matrix.os }}"
@@ -49,10 +54,6 @@ jobs:
     runs-on: ${{ matrix.os }}
     continue-on-error: ${{ matrix.experimental }}
     steps:
-      - name: Cancel previous
-        uses: styfle/cancel-workflow-action@d07a454dad7609a92316b57b23c9ccfd4f59af66 # 0.13.1
-        with:
-          access_token: ${{ github.token }}
       - name: "Check out repository"
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
@@ -89,10 +90,6 @@ jobs:
     runs-on: ${{ matrix.os }}
     continue-on-error: true
     steps:
-      - name: Cancel previous
-        uses: styfle/cancel-workflow-action@d07a454dad7609a92316b57b23c9ccfd4f59af66 # 0.13.1
-        with:
-          access_token: ${{ github.token }}
       - name: "Check out repository"
         uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with: