PSM Interop: add missing GCP service account to the cleanup job (#31577)

Recently we had an issue with Service Account IAM policy getting too large.
RC is the cleanup script missing GCP SA account.
This PR adds adds missing `gcp_service_account` to the cleanup script.

tools/internal_ci/linux/grpc_xds_resource_cleanup.sh

@@ -35,6 +35,7 @@ python3 -m bin.cleanup.cleanup \
     --project=grpc-testing \
     --network=default-vpc \
     --kube_context="${KUBE_CONTEXT}" \
+    --gcp_service_account=xds-k8s-interop-tests@grpc-testing.iam.gserviceaccount.com \
     --resource_prefix='required-but-does-not-matter' \
     --td_bootstrap_image='required-but-does-not-matter' --server_image='required-but-does-not-matter' --client_image='required-but-does-not-matter'
 
@@ -52,6 +53,7 @@ python3 -m bin.cleanup.namespace \
     --network=default-vpc \
     --keep_hours=6 \
     --kube_context="${TARGET_KUBE_CONTEXT}" \
+    --gcp_service_account=xds-k8s-interop-tests@grpc-testing.iam.gserviceaccount.com \
     --resource_prefix='required-but-does-not-matter' \
     --td_bootstrap_image='required-but-does-not-matter' --server_image='required-but-does-not-matter' --client_image='required-but-does-not-matter'
 
@@ -66,5 +68,6 @@ python3 -m bin.cleanup.namespace \
     --network=default-vpc \
     --keep_hours=6 \
     --kube_context="${TARGET_KUBE_CONTEXT}" \
+    --gcp_service_account=xds-k8s-interop-tests@grpc-testing.iam.gserviceaccount.com \
     --resource_prefix='required-but-does-not-matter' \
     --td_bootstrap_image='required-but-does-not-matter' --server_image='required-but-does-not-matter' --client_image='required-but-does-not-matter'