Brittle coupling of OAuth 2.0 scopes in Swagger UI and UserCredentialsProvider

[hannes-ucsc]

azul/lambdas/service/app.py

Line 263 in 4c22bf3

scopes = ('email',)

vs

azul/src/azul/terra.py

Line 274 in a5d0ce8

return ['https://www.googleapis.com/auth/userinfo.email']

They are different (but semantically equivalent), and changing one requires changing the other.

Solve together with #5095