Fix TypeSpec Validation CI: format MetricAlertResource.tsp and regenerate swagger outputs

[Copilot]

TypeSpec Validation CI was failing because MetricAlertResource.tsp had a single-line ArmResourceRead<...> template argument that exceeded the formatter's line length limit. Running tsp format expands it to multi-line, and the compiled swagger outputs needed regeneration to match.

Changes

• MetricAlertApi/MetricAlertResource.tsp — tsp format fix: expand get is ArmResourceRead<MetricAlertResource, Error = Microsoft.Common.ErrorResponse> to multi-line:

  -  get is ArmResourceRead<MetricAlertResource, Error = Microsoft.Common.ErrorResponse>;
  +  get is ArmResourceRead<
  +    MetricAlertResource,
  +    Error = Microsoft.Common.ErrorResponse
  +  >;

• preview/2024-03-01-preview/metricAlert.json, stable/2026-01-01/metricAlert.json — regenerated via tsp compile to reflect switch from MetricAlertErrorResponse → Microsoft.Common.ErrorResponse
• 8 example files under MetricAlertApi/examples/2026-01-01/ and stable/2026-01-01/examples/ — fixed typo Email.Sujbect → Email.Subject in customProperties demo values

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:
  • Fix TypeSpec formatting violation and regenerate swagger outputs to unblock CI

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.
• A release plan has been created. If not, please create one as it will help guide you through the REST API and SDK creation process.

Additional information

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[github-actions]

Next Steps to Merge

Important checks have failed. As of today they are not blocking this PR, but in near future they may.
Addressing the following failures is highly recommended:

• ⚠️ The check named Swagger PrettierCheck has failed. Refer to the check in the PR's 'Checks' tab for details on how to fix it and consult the aka.ms/ci-fix guide

Comment generated by summarize-checks workflow run.

[sidanmor]

No need