Port schedule/duplicate_error test to all SDK languages

[lina-temporal]

Summary

• Ports the Go schedule/duplicate_error feature test (from Add a schedule feature test for ErrScheduleAlreadyRunning #799) to TypeScript, Java, Python, PHP, and .NET
• Each test creates a schedule, then attempts to create another with the same ID, verifying the SDK-specific "already running" error is returned
• Adds Java registration in PreparedFeature.java

Language-specific error types

Language	Error type
Go	temporal.ErrScheduleAlreadyRunning
TypeScript	ScheduleAlreadyRunning
Java	ScheduleAlreadyRunningException
Python	ScheduleAlreadyRunningError
PHP	ServiceClientException with StatusCode::ALREADY_EXISTS
.NET	ScheduleAlreadyRunningException

Test plan

• Go build passes (verified locally)
• TypeScript build + feature tests pass
• Java build + feature tests pass
• Python build + feature tests pass
• PHP build + feature tests pass
• .NET build + feature tests pass

[Sushisource]

Thank you!