chore: revert previous node-version template changes in ci.yaml (#2117)

chore: revert previous node-version template changes

Source-Link: googleapis/synthtool@4b09ede
Post-Processor: gcr.io/cloud-devrel-public-resources/owlbot-nodejs:latest@sha256:b612d739b0533e56ba174526ca339f264b63e911c30d6f83f55b57c38cc6ad2a

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: gcf-owl-bot[bot]

.github/.OwlBot.lock.yaml

@@ -13,5 +13,5 @@
 # limitations under the License.
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-nodejs:latest
-  digest: sha256:1d7c29870723d4d2e32870c6dcdc43d4aa93dcc6519272d025bfcf2ecd48f091
-# created: 2025-08-14T17:16:30.591542591Z
+  digest: sha256:b612d739b0533e56ba174526ca339f264b63e911c30d6f83f55b57c38cc6ad2a
+# created: 2025-08-15T12:36:48.871481111Z

.github/workflows/ci.yaml

@@ -32,7 +32,7 @@ jobs:
       - uses: actions/checkout@v5
       - uses: actions/setup-node@v4
         with:
-          node-version: 22
+          node-version: 18
       - run: node --version
       - run: npm install --engine-strict
         working-directory: .github/scripts
@@ -46,7 +46,7 @@ jobs:
       - uses: actions/checkout@v5
       - uses: actions/setup-node@v4
         with:
-          node-version: 22
+          node-version: 18
       - run: npm install --engine-strict
       - run: npm test
         env:
@@ -57,7 +57,7 @@ jobs:
       - uses: actions/checkout@v5
       - uses: actions/setup-node@v4
         with:
-          node-version: 22
+          node-version: 18
       - run: npm install
       - run: npm run lint
   docs:
@@ -66,7 +66,7 @@ jobs:
       - uses: actions/checkout@v5
       - uses: actions/setup-node@v4
         with:
-          node-version: 22
+          node-version: 18
       - run: npm install
       - run: npm run docs
       - uses: JustinBeckwith/linkinator-action@v1