Populate telemetry for non-action post-job steps

[drielenr]

Summary

Populate StepTelemetry.Type and StepTelemetry.Action for non-action post-job steps.

This is needed for snapshot requests, which are added as RegisterPostJobStep. Currently, action_execution_history telemetry type/action show as empty

issue:

• https://github.com/github/hosted-compute-ims/issues/1639

Changes

• Set Type = "runner" and derive Action from DisplayName for post-job steps

Before:

After:

Testing

• Added RegisterPostJobStep_JobExtensionRunner_DefaultsRunnerTelemetry test to verify that runner-owned post-job steps get default telemetry values.
• Added RegisterPostJobStep_ActionRunner_DoesNotOverrideTelemetry test to ensure that action post-job steps do not have their telemetry values pre-populated, allowing the handler to set them as needed.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds default step telemetry for runner-owned post-job steps while ensuring action post-job steps keep handler-populated telemetry.

Changes:

• Populate StepTelemetry.Type/Action when registering post-job steps that are not IActionRunner.
• Add L0 coverage verifying defaults are applied for JobExtensionRunner and not applied for IActionRunner post steps.

Show a summary per file

File	Description
src/Runner.Worker/ExecutionContext.cs	Adds default telemetry assignment during RegisterPostJobStep for non-action steps.
src/Test/L0/Worker/ExecutionContextL0.cs	Adds tests covering telemetry defaulting vs. non-overriding for action post steps.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 3