deleted pipelines_charts file

it is no longer used now that all the pipeline chart stuff is in 1 file

app/assets/javascripts/pipelines/pipelines_charts.js

-import Chart from 'vendor/Chart';
-
-document.addEventListener('DOMContentLoaded', () => {
-  const chartData = JSON.parse(document.getElementById('pipelinesChartsData').innerHTML);
-  const buildChart = (chartScope) => {
-    const data = {
-      labels: chartScope.labels,
-      datasets: [{
-        fillColor: '#707070',
-        strokeColor: '#707070',
-        pointColor: '#707070',
-        pointStrokeColor: '#EEE',
-        data: chartScope.totalValues,
-      },
-      {
-        fillColor: '#1aaa55',
-        strokeColor: '#1aaa55',
-        pointColor: '#1aaa55',
-        pointStrokeColor: '#fff',
-        data: chartScope.successValues,
-      },
-      ],
-    };
-    const ctx = $(`#${chartScope.scope}Chart`).get(0).getContext('2d');
-    const options = {
-      scaleOverlay: true,
-      responsive: true,
-      maintainAspectRatio: false,
-    };
-    if (window.innerWidth < 768) {
-      // Scale fonts if window width lower than 768px (iPad portrait)
-      options.scaleFontSize = 8;
-    }
-    new Chart(ctx).Line(data, options);
-  };
-
-  chartData.forEach(scope => buildChart(scope));
-});