Geo end-to-end test for NPM registry replication

What does this MR do?

This MR fills a test gap in the Geo end-to-end test suite. Geo recently enabled package file replication and this covers NPM package replication.

It is based on the existing NPM registry spec. There is an open issue to explore how to reduce code duplication; this test will provide test coverage, and then we'll iterate on more efficient code usage.

1. Log into GitLab Geo primary site
2. Create project
3. Publish NPM package associated with project
4. Visit GitLab Geo secondary site
5. Confirm NPM package replicated

Related to gitlab-org/quality/testcases#1026

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content