@google-cloud/billing-budgets API generating failing system tests

[bcoe]

The system tests generated for billing-budgets attempt to load a module called billing, rather than @google-cloud/billing-budgets:

/usr/local/google/home/bencoe/google/nodejs-billing-budgets/system-test/fixtures/sample/src/index.js
  19:25  error  "budgets" is not found                                    node/no-missing-require
  22:9   error  'budgetServiceClient' is assigned a value but never used  no-unused-vars

[alexander-fenster]

Will be taken care of by #697.