Update test_baseline_api_scan.json to valid schema
What does this MR do?
This MR updates the start_time and end_time fields to valid values. As we are now validating schema for reports, this is currently causing any pipelines that use this schema to throw an error. See https://gitlab.com/gitlab-examples/security/security-reports/-/pipelines/546007859/security for an example.
What are the relevant issue numbers?
N/A