rootfs: Make OPA build working in docker for s390x and ppc64le

The commit is to make the OPA build from source working in `ubuntu-rootfs-osbuilder`.
To achieve the goal, the configuration is changed as follows:

- Switch the make target to `ci-build-linux-static` not triggering docker-in-docker build
- Install go in the builder image for s390x and ppc64le

Fixes: #9466

Signed-off-by: Hyounggyu Choi <Hyounggyu.Choi@ibm.com>

tools/osbuilder/rootfs-builder/rootfs.sh

@@ -553,10 +553,9 @@ build_opa_from_source()
 	local opa_repo_url=$1
 	opa_version="$(get_package_version_from_kata_yaml externals.open-policy-agent.version)"
 
-	if [ ${CROSS_BUILD} == "yes" ]; then
-		export GOOS="${TARGET_OS}"
-		export GOARCH="${TARGET_ARCH}}"
-	fi
+	export PATH="$PATH:/usr/local/go/bin"
+	export GOOS="${TARGET_OS}"
+	[ ${CROSS_BUILD} == "yes" ] && export GOARCH="${TARGET_ARCH}" || export GOARCH="$(uname -m)"
 
 	current_dir="$(pwd)"
 	pushd $(mktemp -d) &>/dev/null
@@ -565,7 +564,7 @@ build_opa_from_source()
 		cd opa
 		export WASM_ENABLED=0
 		export DOCKER_RUNNING=0
-		make ci-go-ci-build-linux-static || return 1
+		make ci-build-linux-static || return 1
 
 		info "Copy OPA binary to ${current_dir}/opa"
 		binary_name="_release/${opa_version##v}/opa_${GOOS}_${GOARCH}_static"