Automatic merge from submit-queue (batch tested with PRs 49409, 49352, 49266, 48418)
Use helper to init ClusterIP and NodePort in Create of service
**What this PR does / why we need it**:
Make service `Create` more readable and testable.
- use `initClusterIP` introduced in #46197 to init ClusterIP allocation in service `Create`
- add a new helper `initNodePort` to init NodePort allocation in service `Create`
- TBD: add test case for `initNodePort`. This will cover the NodePort allocation process in `Create`. If this PR makes sense, I will write a test case later.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#35354 (not directly. #35354 was fixed by #46197. The idea of this PR is from https://github.com/kubernetes/kubernetes/pull/46197#discussion_r120910077)
**Special notes for your reviewer**:
/cc @thockin @freehan
**Release note**:
```release-note
NONE
```
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