Fix instance_usage_audit_log v3 follow REST principles

Use query parameter 'before' instead of show.
BTW, add expected_errors decorator.

Partially implements bp v3-api-extension-versioning

DocImpact

Change-Id: If1168c01e6342675370acdf278e1c0317aff93d8
Merge "Fix instance_usage_audit_log v3 follow REST principles"