Automatic merge from submit-queue
GCE: Consume new config value for network project id
This PR will allow users to specify the network's project ID in gce.conf. If it's not specified, it will be filled with `ProjectID`. This means that `network-project-id` is a required field for building a cluster on a shared VPC network. However, this means the field does not need to be specified for GKE clusters on non-shared networks.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
Fixes#48515
**Special notes for your reviewer**:
/assign @bowei @freehan
**Release note**:
```release-note
NONE
```
c02afa6e39