Fix arn table upload on release

[xrmx]

The release pipeline is failing in the publish-lambda-layers job because the expected .arn-file.md is not found by the task trying to upload it.

See https://github.com/elastic/apm-agent-python/actions/runs/16901990644/job/48557443591

[v1v]

See an early error:

• https://github.com/elastic/apm-agent-python/actions/runs/16901990644/job/48557443520#step:3:90

Error: Failed to CreateArtifact: Received non-retryable error: Failed request: (409) Conflict: an artifact with this name already exists on the workflow run

No idea if that's related

[v1v]

#2397 is the fix that @fr4nc1sc0-r4m0n solved it :)