Use java 21 with graal (#11270)

Author: laurit

.github/workflows/reusable-native-tests.yml

@@ -16,13 +16,12 @@ jobs:
       - uses: graalvm/setup-graalvm@2f25c0caae5b220866f732832d5e3e29ff493338 # v1.2.1.1
         with:
           version: "latest"
-          java-version: "17"
+          java-version: "21"
           components: "native-image"
       - name: Running test
         run: |
           echo "GRAALVM_HOME: $GRAALVM_HOME"
           echo "JAVA_HOME: $JAVA_HOME"
           java --version
-          gu --version
           native-image --version
           ./gradlew nativeTest