403 permission denied errors in some libraries with always_use_jwt_access = True #929

@parthea noticed some library system and sample tests failing in PRs adding always_use_jwt_access (see #920)

There are three slightly different error messages:

1. google.api_core.exceptions.PermissionDenied: 403 Provided scope(s) are not authorized

   • feat: add always_use_jwt_access python-asset#211 - Strangely, only one sample fails. The other 11 sample tests passed.

   • feat: add always_use_jwt_access python-speech#184

2. google.api_core.exceptions.PermissionDenied: 403 The caller does not have permission

   • feat: add always_use_jwt_access python-videointelligence#168

3. google.api_core.exceptions.PermissionDenied: 403 User does not have sufficient permissions for this property. To learn more about Property ID, see https://developers.google.com/analytics/devguides/reporting/data/v1/property-id.

   • feat: add always_use_jwt_access python-analytics-data#92

Sample tests in many other repositories did pass, and I do not see an obvious difference between these APIs and the ones above.

• feat: add always_use_jwt_access python-kms#129
• feat: add always_use_jwt_access python-secret-manager#137
• feat: add always_use_jwt_access python-automl#175