chore(cc): simplify the asynchronous code of resource CC central network and resource CC central network policy apply

[profoundwu]

What this PR does / why we need it: simplify the asynchronous code of resource CC central network and resource CC central network policy apply Which issue this PR fixes: (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged) fixes #xxx

Special notes for your reviewer:

Release note:

1. simplify the asynchronous code of resource CC central network and resource CC central network policy apply

PR Checklist

• [x] Tests added/passed.
• [ ] Documentation updated.
• [ ] Schema updated.

Acceptance Steps Performed

make testacc TEST="./huaweicloud/services/acceptance/cc" TESTARGS="-run TestAccCentralNetwork_basic"
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./huaweicloud/services/acceptance/cc -v -run TestAccCentralNetwork_basic -timeout 360m -parallel 4
=== RUN   TestAccCentralNetwork_basic
=== PAUSE TestAccCentralNetwork_basic
=== CONT  TestAccCentralNetwork_basic
--- PASS: TestAccCentralNetwork_basic (62.80s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/cc        62.846s
huawei@ecs-wubo:~/go/src/github.com/huaweicloud/terraform-provider-huaweicloud$ make testacc TEST="./huaweicloud/services/acceptance/cc" TESTARGS="-run TestAccCentralNetworkPolicyApply_basic"
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./huaweicloud/services/acceptance/cc -v -run TestAccCentralNetworkPolicyApply_basic -timeout 360m -parallel 4
=== RUN   TestAccCentralNetworkPolicyApply_basic
=== PAUSE TestAccCentralNetworkPolicyApply_basic
=== CONT  TestAccCentralNetworkPolicyApply_basic
--- PASS: TestAccCentralNetworkPolicyApply_basic (124.49s)
PASS
ok      github.com/huaweicloud/terraform-provider-huaweicloud/huaweicloud/services/acceptance/cc        124.548s