Remove the Issue Summarizer workflow and update GenAI prompt generation

[pelikhan]

• Deleted the issue-summarizer-genaiscript.md workflow file.
• Refactored the prompt generation logic in shared/genaiscript.md to use echo commands instead of sed for better readability and maintainability.
• Updated the smoke-genaiscript.lock.yml and smoke-genaiscript.md files to trigger on pushes to the lock file, ensuring workflows are executed on relevant changes.

[pelikhan]

@copilot the imports section should not be part of the rendered prompt. See below when rendering smoke-genaiscript.md

- name: Create prompt
        env:
          GITHUB_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
          GITHUB_AW_SAFE_OUTPUTS: ${{ env.GITHUB_AW_SAFE_OUTPUTS }}
        run: |
          mkdir -p $(dirname "$GITHUB_AW_PROMPT")
          cat > $GITHUB_AW_PROMPT << 'EOF'
          
          ```yaml
          ---
          imports:
            - shared/genaiscript.md
          ---
          ```
          
          Review the last 5 merged pull requests in this repository and post summary in an issue.
          
          EOF

[Copilot]

@pelikhan I've opened a new pull request, #1503, to work on those changes. Once the pull request is ready, I'll request review from you.

[github-actions]

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