remove duplicate mask constant

assets/src/scripts/monitoring-location/components/hydrograph/time-series-lines.js

 import {line as d3Line} from 'd3-shape';
+import {HASH_ID} from './selectors/iv-data';
 
-export const HASH_ID = {
-    primary: 'hash-45',
-    compare: 'hash-135'
-};
 
 const CIRCLE_RADIUS_SINGLE_PT = 1;