Update Node.js to 10.15.3 in CI template for Hexo

What does this MR do?

Updates Node.js to 10.15.3 in CI template for Hexo so as for users not to use Node.js 6.x (EOLed in 2019-04). Also follows the official installation and improves some developer experience by suppressing warning from npm install when no package.json in the CI target repo.

What are the relevant issue numbers?

Part of #58748 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [n/a] Documentation created/updated via this MR
• [n/a] Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• [n/a] Conforms to the database guides
• [n/a] Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• [n/a] Security reports checked/validated by reviewer