app-root: Remove stub routes

[goplayoutside3]

Package

app-root

Linked Issue and/or Talk Post

Corresponds to #6335
Toward: #6331

Describe your changes

• We do NOT want search engines to find stub routes in the app such as /projects so I removed those.
• The liveness probe of app-root previously relied on /users but there's no page at that route so I changed it to /about.

How to Review

• This is mainly tested by the CI builds and we'll need to check that fe-root.preview deploys correctly.

Checklist

PR Creator - Please cater the checklist to fit the review needed for your code changes.
PR Reviewer - Use the checklist during your review. Each point should be checkmarked or discussed before PR approval.

General

• Tests are passing locally and on Github
• Documentation is up to date and changelog has been updated if appropriate
• You can yarn panic && yarn bootstrap or docker-compose up --build and FEM works as expected
• FEM works in all major desktop browsers: Firefox, Chrome, Edge, Safari (Use Browserstack account as needed)

[coveralls]

coverage: 78.557% (+0.04%) from 78.515%
when pulling fabb223 on remove-stub-pages
into 79c80fa on master.

[goplayoutside3]

This will be deployed alongside zooniverse/static#380 on Monday 👍