Allow targeting of a URL in proxy template

[scbedd]

See title. Based on follow-up discussion with @heaths

[heaths]

Not blocking despite my question because maybe it's fine. Just not expected since the diff was unexpected.

[Copilot]

Pull request overview

This PR updates the shared test-proxy pipeline templates so callers can override the proxy bind URL instead of always using the default localhost:5000 endpoint.

Changes:

• Adds a new proxyUrl parameter to both common test-proxy templates.
• Passes proxyUrl through to the proxy startup command via start ... -- --urls.
• Switches the post-start Admin/IsAlive probe to use the configured URL.

Show a summary per file

File	Description
eng/common/testproxy/test-proxy-tool.yml	Adds configurable proxy URL support to the standard test-proxy template for startup and health checks.
eng/common/testproxy/test-proxy-standalone-tool.yml	Mirrors the same configurable proxy URL behavior in the standalone test-proxy template.

Copilot's findings

Comments suppressed due to low confidence (2)

eng/common/testproxy/test-proxy-tool.yml:110

• --urls accepts ASP.NET-style bind strings such as http://localhost:9000;https://localhost:9001 and wildcard hosts like http://0.0.0.0:0, but this readiness check treats proxyUrl as a single client URL by appending /Admin/IsAlive. Those valid bind values produce an invalid or unroutable probe URI, so the template can fail even when the proxy starts successfully.

                Write-Host "Invoke-WebRequest -Uri `"${{ parameters.proxyUrl }}/Admin/IsAlive`" | Out-Null"
                Invoke-WebRequest -Uri "${{ parameters.proxyUrl }}/Admin/IsAlive" | Out-Null

eng/common/testproxy/test-proxy-standalone-tool.yml:98

• --urls accepts ASP.NET-style bind strings such as http://localhost:9000;https://localhost:9001 and wildcard hosts like http://0.0.0.0:0, but this readiness check treats proxyUrl as a single client URL by appending /Admin/IsAlive. Those valid bind values produce an invalid or unroutable probe URI, so the template can fail even when the proxy starts successfully.

                Write-Host "Invoke-WebRequest -Uri `"${{ parameters.proxyUrl }}/Admin/IsAlive`" | Out-Null"
                Invoke-WebRequest -Uri "${{ parameters.proxyUrl }}/Admin/IsAlive" | Out-Null

• Files reviewed: 2/2 changed files
• Comments generated: 2

[azure-sdk]

The following pipelines have been queued for testing:
java - template
java - template - tests
js - template
net - template
net - template - tests
python - template
python - template - tests
You can sign off on the approval gate to test the release stage of each pipeline.
See eng/common workflow

[heaths]

net - template's Build job failed, though the rest worked. I'm kicking it to see if it works next time.

[azure-sdk]

The following pipelines have been queued for testing:
java - template
java - template - tests
js - template
net - template
net - template - tests
python - template
python - template - tests
You can sign off on the approval gate to test the release stage of each pipeline.
See eng/common workflow