Sync post release workflow a bit more with other Java repos (#7755)

Author: trask

.github/workflows/release.yml

@@ -133,7 +133,7 @@ jobs:
           echo "version=$VERSION" >> $GITHUB_OUTPUT
           echo "prior-version=$PRIOR_VERSION" >> $GITHUB_OUTPUT
 
-  update-apidiff-baseline-and-docs-to-released-version:
+  post-release-updates:
     permissions:
       contents: write # for git push to PR branch
     runs-on: ubuntu-latest
@@ -178,6 +178,15 @@ jobs:
             sleep 60
           done
 
+      - name: Set up JDK for running Gradle
+        uses: actions/setup-java@dded0888837ed1f317902acf8a20df0ad188d165 # v5.0.0
+        with:
+          distribution: temurin
+          java-version: 17
+
+      - name: Set up Gradle
+        uses: gradle/actions/setup-gradle@4d9f0ba0025fe599b4ebab900eb7f3a1d93ef4c2 # v5.0.0
+
       - name: Update apidiff baseline
         env:
           VERSION: ${{ needs.release.outputs.version }}
@@ -209,9 +218,9 @@ jobs:
           # not using secrets.GITHUB_TOKEN since pull requests from that token do not run workflows
           GH_TOKEN: ${{ steps.otelbot-token.outputs.token }}
         run: |
-          message="Update apidiff baseline and documentation versions to released version $VERSION"
-          body="Update apidiff baseline and documentation versions to released version \`$VERSION\`."
-          branch="otelbot/update-apidiff-baseline-and-documentation-to-released-version-${VERSION}"
+          message="Post-release updates for $VERSION"
+          body="Post-release updates for \`$VERSION\`."
+          branch="otelbot/post-release-updates-${VERSION}"
 
           git checkout -b $branch
           git commit -m "$message"