UriOverrideEnforceMode mode is to define enforcing mode for
the override modes.
Values:
URI_OVERRIDE_ENFORCE_MODE_UNSPECIFIED (0):
OverrideMode Unspecified. Defaults to ALWAYS.
IF_NOT_EXISTS (1):
In the IF_NOT_EXISTS mode, queue-level configuration is only
applied where task-level configuration does not exist.
ALWAYS (2):
In the ALWAYS mode, queue-level configuration
overrides all task-level configuration