[FLINK-3055] [runtime] Remove redundant version of "Executionvertex.getSubTaskIndex()"

This closes #1438

flink-runtime-web/src/main/java/org/apache/flink/runtime/webmonitor/handlers/SubtaskExecutionAttemptAccumulatorsHandler.java

@@ -46,7 +46,7 @@ public class SubtaskExecutionAttemptAccumulatorsHandler extends AbstractSubtaskA
 
 		gen.writeStartObject();
 
-		gen.writeNumberField("subtask", execAttempt.getVertex().getSubTaskIndex());
+		gen.writeNumberField("subtask", execAttempt.getVertex().getParallelSubtaskIndex());
 		gen.writeNumberField("attempt", execAttempt.getAttemptNumber());
 		gen.writeStringField("id", execAttempt.getAttemptId().toShortString());
 		

flink-runtime-web/src/main/java/org/apache/flink/runtime/webmonitor/handlers/SubtaskExecutionAttemptDetailsHandler.java

@@ -78,7 +78,7 @@ public class SubtaskExecutionAttemptDetailsHandler extends AbstractSubtaskAttemp
 		JsonGenerator gen = JsonFactory.jacksonFactory.createJsonGenerator(writer);
 
 		gen.writeStartObject();
-		gen.writeNumberField("subtask", execAttempt.getVertex().getSubTaskIndex());
+		gen.writeNumberField("subtask", execAttempt.getVertex().getParallelSubtaskIndex());
 		gen.writeStringField("status", status.name());
 		gen.writeNumberField("attempt", execAttempt.getAttemptNumber());
 		gen.writeStringField("host", locationString);

flink-runtime/src/main/java/org/apache/flink/runtime/executiongraph/ExecutionVertex.java

@@ -179,10 +179,6 @@ public class ExecutionVertex implements Serializable {
 				getTotalNumberOfParallelSubtasks());
 	}
 
-	public int getSubTaskIndex() {
-		return subTaskIndex;
-	}
-
 	public int getTotalNumberOfParallelSubtasks() {
 		return this.jobVertex.getParallelism();
 	}