fix(core): Fix execution cancellation issues in scaling mode

[ivov]

Summary

This PR fixes a number of issues with execution cancellation in scaling mode:

1. After the introduction of ExecutionCancelledError if you abort an active production execution in scaling mode, the execution ends up with error status rather than canceled. Only executions aborted after being dequeued are affected. This PR is a hotfix for the issue - see before and after.
2. For a long time we have been sending two abort-job messages to a worker for a single cancellation. More context here. This PR prevents the second message.
3. Cancelling an execution produces not one but two error logs with full stack traces, see here. ExecutionCancelledError is not an actual error to handle and the cancellation is already being reported normally via debug logs, so this PR removes that noise, which can be confusing for users as well.

Related Linear tickets, Github issues, and Community forum posts

None, I noticed these issues by chance.

Review / Merge checklist

• PR title and summary are descriptive
• Docs updated
• Tests included (legacy flow not easily testable)
• PR Labeled with release/backport

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
packages/core/src/error-reporter.ts	50.00%	1 Missing ⚠️

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