Release 1810

Trello card

https://trello.com/c/vMG7Hdpq/

Context

The current healthcheck is ambiguous as to what API checks.
It also reports false positive results for the dfe signin check, when the DfE api is either disabled in our end or the credentials are missing.

Changes proposed in this pull request

• Remove the guard clause that checks if the dfe auth is ok and let the actual request decides the results. Also, change the returned values to boolean.
• Rename the auth and the api labels in the healthcheck results to be more explicit

Guidance to review

Visit /healthcheck

Before

{"deployment_id":"Prod-7166","app_sha":"sha-","auth":{},"api":true,"db":true,"cache":true,"healthy":true,"status":"OK"}

After

{"deployment_id":"Prod-7166","app_sha":"sha-","dfe_auth":true,"gitis_api":true,"db":true,"cache":true,"healthy":true,"status":"OK"}