Add logging to debug empty outputs in subworkflow (#274)

## Overview
Add some logging to better narrow missing outputs to either admin or propeller paths. In support of https://unionai.atlassian.net/browse/CASE-643

## Test Plan
Unit tests pass + manual inspection

## Rollout Plan (if applicable)
Pull over to cloud and deploy admin + propeller

## Upstream Changes
Should this change be upstreamed to OSS (flyteorg/flyte)? If so, please check this box for auditing. Note, this is the responsibility of each developer. See [this guide](https://unionai.atlassian.net/wiki/spaces/ENG/pages/447610883/Flyte+-+Union+Cloud+Development+Runbook/#When-are-versions-updated%3F).
- [ ] To be upstreamed

## Issue
ref CLD-922

flyteadmin/pkg/rpc/adminservice/execution.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/flyteorg/flyte/flyteadmin/pkg/rpc/adminservice/util"
 	"github.com/flyteorg/flyte/flyteidl/gen/pb-go/flyteidl/admin"
+	"github.com/flyteorg/flyte/flytestdlib/logger"
 )
 
 func (m *AdminService) CreateExecution(
@@ -139,6 +140,10 @@ func (m *AdminService) GetExecutionData(
 		return nil, util.TransformAndRecordError(err, &m.Metrics.executionEndpointMetrics.getData)
 	}
 	m.Metrics.executionEndpointMetrics.getData.Success()
+	// DEBUG: CASE-643
+	if response.GetFullOutputs().GetLiterals() == nil || len(response.GetFullOutputs().GetLiterals()) == 0 {
+		logger.Debugf(ctx, "GetExecutionData().FullOutputs empty for execution %v. FullOutputs: %v. Outputs: %v", request.GetId(), response.GetFullOutputs(), response.GetOutputs())
+	}
 	return response, nil
 }
 

flytepropeller/pkg/controller/nodes/subworkflow/launchplan.go

@@ -210,6 +210,10 @@ func (l *launchPlanHandler) CheckLaunchPlanStatus(ctx context.Context, nCtx inte
 
 			oInfo = &handler.OutputInfo{OutputURI: outputFile}
 		}
+		// DEBUG: CASE-643
+		if outputs.GetLiterals() == nil || len(outputs.GetLiterals()) == 0 {
+			logger.Debugf(ctx, "GetStatus() outputs empty for execution %v. Closure: %v. Outputs: %v", childID, wfStatusClosure, outputs)
+		}
 
 		return handler.DoTransition(handler.TransitionTypeEphemeral, handler.PhaseInfoSuccess(&handler.ExecutionInfo{
 			WorkflowNodeInfo: &handler.WorkflowNodeInfo{LaunchedWorkflowID: childID},