Bugfix: ImportWorkflow should always clear mutable state cache (#5039)

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**What changed?**
* ImportWorkflow should always clear "cached" mutable state since 
  * shared mutable state will at most be used once
  * shared mutable state may contain changes not persisted to DB

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service/history/ndc/history_importer.go

@@ -145,12 +145,11 @@ func (r *HistoryImporterImpl) ImportWorkflow(
 		return nil, err
 	}
 	defer func() {
-		if rec := recover(); rec != nil {
-			ndcWorkflow.GetReleaseFn()(errPanic)
-			panic(rec)
-		} else {
-			ndcWorkflow.GetReleaseFn()(retError)
-		}
+		// it is ok to clear everytime this function is invoked
+		// mutable state will be at most initialized once from shard mutable state cache
+		// mutable state will be usually initialized from input token
+		ndcWorkflow.GetContext().Clear()
+		ndcWorkflow.GetReleaseFn()(retError)
 	}()
 
 	if len(eventsSlice) != 0 {

tests/ndc/ndc_test.go

@@ -2220,17 +2220,17 @@ func (s *nDCFunctionalTestSuite) importEvents(
 		resp, err := historyClient.ImportWorkflowExecution(s.newContext(), req)
 		s.NoError(err, "Failed to import history event")
 		token = resp.Token
+	}
 
-		if verifyWorkflowNotExists {
-			_, err := historyClient.GetMutableState(s.newContext(), &historyservice.GetMutableStateRequest{
-				NamespaceId: s.namespaceID.String(),
-				Execution: &commonpb.WorkflowExecution{
-					WorkflowId: workflowID,
-					RunId:      runID,
-				},
-			})
-			s.IsType(&serviceerror.NotFound{}, err)
-		}
+	if verifyWorkflowNotExists {
+		_, err := historyClient.GetMutableState(s.newContext(), &historyservice.GetMutableStateRequest{
+			NamespaceId: s.namespaceID.String(),
+			Execution: &commonpb.WorkflowExecution{
+				WorkflowId: workflowID,
+				RunId:      runID,
+			},
+		})
+		s.IsType(&serviceerror.NotFound{}, err)
 	}
 
 	req := &historyservice.ImportWorkflowExecutionRequest{