Use explicit env.VERSION image tag in autoinstrumentation Docker Scout + Jira steps

[Copilot]

This PR addresses the review comment about unreliable use of steps.meta.outputs.tags[0] from docker/metadata-action (multi-line output). It switches affected workflow inputs to an explicit image reference derived from env.VERSION.

• Scope

  • Updated only .github/workflows/build_publish_image_autoinstrumentation.yaml
  • No changes outside the referenced review comment scope

• Workflow input fix

  • Replaced indexed metadata tag usage in:
    • Docker Scout CVE scan image input
    • Jira action image-tag input
  • New value uses a deterministic explicit tag:
    • ${{ github.repository_owner }}/autoinstrumentation-python:${{ env.VERSION }}

• Before/after

# before
image: ${{ steps.meta.outputs.tags[0] }}
image-tag: ${{ steps.meta.outputs.tags[0] }}

# after
image: ${{ github.repository_owner }}/autoinstrumentation-python:${{ env.VERSION }}
image-tag: ${{ github.repository_owner }}/autoinstrumentation-python:${{ env.VERSION }}