Update eslint analyzer dependencies

What does this MR do?

• Update eslint to 7.15.0.
• Update base image to node15.4-alpine3.12.
• Update babel/cli to v7.12.10.
• Update babel/core to v7.12.10.
• Update babel/plugin-proposal-numeric-separator to v7.12.7.
• Update babel/plugin-proposal-optional-chaining to v7.12.7.
• Update babel/preset-env to v7.12.11.
• Update babel/preset-react to v7.12.10.

What are the relevant issue numbers?

• https://gitlab.com/gitlab-org/security-products/release/-/issues/104

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer