added GCP auth to Java Dataflow V2 streaming validates runner (#38027)

Author: aIbrahiim

.github/workflows/beam_PostCommit_Java_ValidatesRunner_Dataflow_V2_Streaming.yml

@@ -76,6 +76,13 @@ jobs:
         uses: ./.github/actions/setup-environment-action
         with:
           java-version: default
+      - name: Authenticate to GCP
+        uses: google-github-actions/auth@7c6bc770dae815cd3e89ee6cdf493a5fab2cc093
+        with:
+          service_account: ${{ secrets.GCP_SA_EMAIL }}
+          credentials_json: ${{ secrets.GCP_SA_KEY }}
+      - name: Set up Cloud SDK
+        uses: google-github-actions/setup-gcloud@aa5489c8933f4cc7a4f7d45035b3b1440c9c10db
       - name: run validatesRunnerV2Streaming script
         uses: ./.github/actions/gradle-command-self-hosted-action
         with: