Bump Node.js version to >=20.x in gitlab-vscode-build image

MR: Update NodeJS to V22 gitlab-vscode-build (!876 - merged)

Description

The gitlab-vscode-build image used by the GitLab VSCode Fork and the GitLab Web IDE projects to build the VSCode editor has Node.js v18.x installed. From VSCode 1.92.x onward, the development requirements bump Node.js version to >=20.x. We should bump Node.js version to the latest supported version that allows us to build VSCode in these projects.

Acceptance criteria

• Identify which Node.js >= 20.x we can use to build newer versions of VSCode.
• Set that version of Node.js in the follow Dockerfile https://gitlab.com/gitlab-org/gitlab-build-images/-/blob/master/Dockerfile.gitlab-vscode-build?ref_type=heads#L8.