Fix-ScheduledUniverse-GetTriggerTimes-endTimeUtc-bound-handling

[aiSynergy37]

Fixes #9349.

Summary

• ScheduledUniverse.GetTriggerTimes now stops yielding once the next trigger is greater than endTimeUtc.
• Start and end bounds are now documented as inclusive when matching a trigger time.
• Added ScheduledUniverseTests.TimeTriggeredRespectsEndTimeUtcTimePart regression test.

Validation

• dotnet build Tests\QuantConnect.Tests.csproj --no-restore passed.
• dotnet test with ScheduledUniverseTests filter builds but test host crashes in this environment due missing local data path and pythonnet GIL finalizer issue.