[SPARK-45761][K8S][INFRA][DOCS] Upgrade Volcano to 1.8.1

### What changes were proposed in this pull request?

This PR aims to upgrade `Volcano` to 1.8.1 in K8s integration test document and GitHub Action job.

### Why are the changes needed?

To bring the latest feature and bug fixes in addition to the test coverage for Volcano scheduler 1.8.1.

- https://github.com/volcano-sh/volcano/releases/tag/v1.8.1
  - volcano-sh/volcano#3101

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

Pass the CIs.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #43624 from dongjoon-hyun/SPARK-45761.

Authored-by: Dongjoon Hyun <dhyun@apple.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

.github/workflows/build_and_test.yml

@@ -1063,7 +1063,7 @@ jobs:
           export PVC_TESTS_VM_PATH=$PVC_TMP_DIR
           minikube mount ${PVC_TESTS_HOST_PATH}:${PVC_TESTS_VM_PATH} --gid=0 --uid=185 &
           kubectl create clusterrolebinding serviceaccounts-cluster-admin --clusterrole=cluster-admin --group=system:serviceaccounts || true
-          kubectl apply -f https://raw.githubusercontent.com/volcano-sh/volcano/v1.8.0/installer/volcano-development.yaml || true
+          kubectl apply -f https://raw.githubusercontent.com/volcano-sh/volcano/v1.8.1/installer/volcano-development.yaml || true
           eval $(minikube docker-env)
           build/sbt -Psparkr -Pkubernetes -Pvolcano -Pkubernetes-integration-tests -Dspark.kubernetes.test.driverRequestCores=0.5 -Dspark.kubernetes.test.executorRequestCores=0.2 -Dspark.kubernetes.test.volcanoMaxConcurrencyJobNum=1 -Dtest.exclude.tags=local "kubernetes-integration-tests/test"
       - name: Upload Spark on K8S integration tests log files

resource-managers/kubernetes/integration-tests/README.md

@@ -329,11 +329,11 @@ You can also specify your specific dockerfile to build JVM/Python/R based image
 
 ## Requirements
 - A minimum of 6 CPUs and 9G of memory is required to complete all Volcano test cases.
-- Volcano v1.8.0.
+- Volcano v1.8.1.
 
 ## Installation
 
-    kubectl apply -f https://raw.githubusercontent.com/volcano-sh/volcano/v1.8.0/installer/volcano-development.yaml
+    kubectl apply -f https://raw.githubusercontent.com/volcano-sh/volcano/v1.8.1/installer/volcano-development.yaml
 
 ## Run tests
 
@@ -354,5 +354,5 @@ You can also specify `volcano` tag to only run Volcano test:
 
 ## Cleanup Volcano
 
-    kubectl delete -f https://raw.githubusercontent.com/volcano-sh/volcano/v1.8.0/installer/volcano-development.yaml
+    kubectl delete -f https://raw.githubusercontent.com/volcano-sh/volcano/v1.8.1/installer/volcano-development.yaml