Update required Node.js version to 14.17.5

What does this MR do and why?

This MR updates the Node.js version in .tool-versions and .nvmrc to 14.17.5 which is consistent with:

• https://gitlab.com/gitlab-org/gitlab-ui/-/blob/main/.tool-versions
• https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/.tool-versions

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.