delete duplicate elapsed time in phase from saves

[drbergman]

Still recording this information, just only one time. See

• Add to labels:

  PhysiCell/modules/PhysiCell_MultiCellDS.cpp

  Lines 281 to 283 in b35d835

  	// <label index="8" size="1">elapsed_time_in_phase</label>
  	add_variable_to_labels( data_names,data_units,data_start_indices,data_sizes,
  	"elapsed_time_in_phase" , "min" , 1 );

• Write data:

  PhysiCell/modules/PhysiCell_MultiCellDS.cpp

  Lines 799 to 800 in b35d835

  	// name = "elapsed_time_in_phase";
  	std::fwrite( &( pCell->phenotype.cycle.data.elapsed_time_in_phase ) , sizeof(double) , 1 , fp );

This mirrors a PR in the upstream PhysiCell repo: MathCancer#380