changing ref back to ChildResource as asked by breaking change team

[sssharma24]

ARM (Control Plane) API Specification Update Pull Request

Tip

Overwhelmed by all this guidance? See the Getting help section at the bottom of this PR description.

PR review workflow diagram

Please understand this diagram before proceeding. It explains how to get your PR approved & merged.

Purpose of this PR

What's the purpose of this PR? Check the specific option that applies. This is mandatory!

• New resource provider.
• New API version for an existing resource provider. (If API spec is not defined in TypeSpec, the PR should have been created in adherence to OpenAPI specs PR creation guidance).
• Update existing version for a new feature. (This is applicable only when you are revising a private preview API version.)
• Update existing version to fix OpenAPI spec quality issues in S360.
• Convert existing OpenAPI spec to TypeSpec spec (do not combine this with implementing changes for a new API version).
• Other, please clarify:
  • update existing version due to breaking changes

Due diligence checklist

To merge this PR, you must go through the following checklist and confirm you understood
and followed the instructions by checking all the boxes:

• I confirm this PR is modifying Azure Resource Manager (ARM) related specifications, and not data plane related specifications.
• I have reviewed following Resource Provider guidelines, including
  ARM resource provider contract and
  REST guidelines (estimated time: 4 hours).
  I understand this is required before I can proceed to the diagram Step 2, "ARM API changes review", for this PR.

Additional information

Viewing API changes

For convenient view of the API changes made by this PR, refer to the URLs provided in the table
in the Generated ApiView comment added to this PR. You can use ApiView to show API versions diff.

Suppressing failures

If one or multiple validation error/warning suppression(s) is detected in your PR, please follow the
suppressions guide to get approval.

Getting help

• First, please carefully read through this PR description, from top to bottom. Please fill out the Purpose of this PR and Due diligence checklist.
• If you don't have permissions to remove or add labels to the PR, request write access per aka.ms/azsdk/access#request-access-to-rest-api-or-sdk-repositories
• To understand what you must do next to merge this PR, see the Next Steps to Merge comment. It will appear within few minutes of submitting this PR and will continue to be up-to-date with current PR state.
• For guidance on fixing this PR CI check failures, see the hyperlinks provided in given failure
  and https://aka.ms/ci-fix.
• For help with ARM review (PR workflow diagram Step 2), see https://aka.ms/azsdk/pr-arm-review.
• If the PR CI checks appear to be stuck in queued state, please add a comment with contents /azp run.
  This should result in a new comment denoting a PR validation pipeline has started and the checks should be updated after few minutes.
• If the help provided by the previous points is not enough, post to https://aka.ms/azsdk/support/specreview-channel and link to this PR.

[openapi-pipeline-app]

Next Steps to Merge

✅ All automated merging requirements have been met! To get your PR merged, see aka.ms/azsdk/specreview/merge.

[openapi-pipeline-app]

Generated ApiView

Language	Package Name	ApiView Link
Go	sdk/resourcemanager/network/armnetwork	https://apiview.dev/Assemblies/Review/1b263a329090477991c0a7b7b0ae21d7?revisionId=c02cc292f7194b56b8c97c30171a6c72
JavaScript	@azure/arm-network	https://apiview.dev/Assemblies/Review/c13fd66ecbcc4c2a9995c8a1f4187240?revisionId=b4e55286ceb04a0e908230f8b65ebec7
Swagger	Microsoft.Network	https://apiview.dev/Assemblies/Review/9a91f46aa0a846acaae91aba821517fb?revisionId=1eea9c33e77040ad806fd8811b7f46a1

[sssharma24]

ARM reviewers recommended us to switch from ChildResource to ProxyResource and use common type refs due to new ARM standards but changing this in network.json would cause errors for other teams. Hence as a workaround, we copied the definitions and started using CommonProxyResource. This dropped the property etag which was previously available to the customer and this breaking change cannot be approved as the service is already in use. That's why we are reverting to ChildResource again. #30560