Make the saga diagram use toLocaleString as the rest of the diagrams do

[cquirosj]

Make the saga diagram use toLocaleString as the rest of the diagrams do.

What is included in this PR?

• Make the SagaDiagram render date and time consistently with the way the other diagrams render date and time by also using toLocaleString
• Make two test scenarios use the same test code by passing scenario specifics through test.each, as they were almost identical.
• Improve test reliability by using toLocaleString() for date assertions, ensuring tests remain stable across different developer environments and OS localization settings (e.g., en-US vs en-AU). This approach balances the gold standard of hardcoded assertions that don't require computation or duplicate the system under test (SUT) code, against the practical need for environment-independent tests. While this duplicates formatting logic from the implementation, it preserves the test's core intent, verifying date ordering and timezone localization, without importing anything from the internals of the component under test.
  • Fixes Locale-sensitive datetime formatting causes test failures on non-US locales #2480