[otel] End all recording spans on non-terminal invocations

[zhongkechen]

Summary

The Java OTel plugins intentionally drop references to recording spans without ending them when a durable execution returns a non-terminal status.

Affected behavior:

• ExecutionOtelPlugin clears open operation and attempt spans during invocation cleanup without ending them.
• Both ExecutionOtelPlugin and InvocationOtelPlugin drop the execution-scoped Workflow span on PENDING or RETRYING.

OpenTelemetry spans are only complete and eligible for processing/export after Span.end() is called.

Evidence

• otel-plugin/src/main/java/software/amazon/lambda/durable/otel/ExecutionOtelPlugin.java
  • onInvocationEnd clears operationSpans and attemptSpans without ending the spans.
  • The non-terminal workflow path clears workflowSpan without ending it.
• otel-plugin/src/main/java/software/amazon/lambda/durable/otel/InvocationOtelPlugin.java
  • The non-terminal workflow path clears workflowSpan without ending it.
• ExecutionOtelPluginTest.nonTerminalInvocation_doesNotExportWorkflowSpan codifies the unended workflow behavior.
• ExecutionOtelPluginTest.operationNotCompleted_notEndedAtInvocationEnd explicitly requires an open operation span not to be ended.
• InvocationOtelPluginTest.workflowSpan_notExportedOnNonTerminal codifies the same workflow behavior.

OpenTelemetry requirement

The Trace API defines End as the operation that completes a span and makes it ready for delivery through the configured span processor:

https://opentelemetry.io/docs/specs/otel/trace/api/#end

Impact

• Span processors can observe span starts without corresponding ends.
• Processor state or references may remain live across warm Lambda invocations.
• Re-created deterministic spans can produce repeated starts for the same logical span ID.
• The behavior prevents a strict OpenTelemetry compliance claim.

Acceptance criteria

• Every recording span created by either Java OTel plugin is ended exactly once.
• Non-terminal workflow and suspended-operation behavior does not rely on abandoning a recording span.
• Cross-invocation workflow and operation correlation remains intact.
• Tests retain span references and assert that they are no longer recording after invocation cleanup.
• Tests cover PENDING, RETRYING, terminal success, and terminal failure for both plugin variants.

Related cross-SDK issue: aws/aws-durable-execution-sdk-python#642