test: update tests to graalvm 25

Author: mpeddada1

.kokoro/build.sh

@@ -80,6 +80,18 @@ graalvm)
     # Run Unit and Integration Tests with Native Image
     bash .kokoro/populate-secrets.sh
     export GOOGLE_APPLICATION_CREDENTIALS="${KOKORO_GFILE_DIR}/secret_manager/java-it-service-account"
+    echo "Install GraalVM 25"
+    echo "$JAVA_HOME"
+    pwd
+    mkdir -p ~/tools/jdk
+    cd ~/tools/jdk
+    wget https://download.oracle.com/graalvm/25/latest/graalvm-jdk-25_linux-x64_bin.tar.gz
+    tar -xf graalvm-jdk-25_linux-x64_bin.tar.gz
+    export JAVA_HOME=~/tools/jdk/graalvm-jdk-25+37.1
+    export PATH=$JAVA_HOME/bin:$PATH
+    java -version
+    echo "Running native image tests..."
+    cd "${scriptDir}/.."
     mvn -B ${INTEGRATION_TEST_ARGS} -ntp -Pnative -Pnative-test -Pslf4j2x test -pl 'oauth2_http'
     RETURN_CODE=$?
     ;;