graph: change tick decimal calculation for y-axis

Fixes #8872. Use the automatic calculation by Flot to get the
number of decimal places for ticks on the y-axis rather than
the number of decimal places for the min value.

public/app/plugins/panel/graph/graph.ts

@@ -588,7 +588,6 @@ coreModule.directive('grafanaGraph', function($rootScope, timeSrv, popoverSrv) {
           if (axis.ticks[axis.ticks.length - 1] > axis.max) {
             axis.max = axis.ticks[axis.ticks.length - 1];
           }
-          axis.tickDecimals = decimalPlaces(min);
         } else {
           axis.ticks = [1, 2];
           delete axis.min;

public/app/plugins/panel/graph/specs/graph_specs.ts

@@ -139,8 +139,6 @@ describe('grafanaGraph', function() {
       expect(axisAutoscale.ticks.length).to.be(8);
       expect(axisAutoscale.ticks[0]).to.be(0.001);
       expect(axisAutoscale.ticks[7]).to.be(10000);
-      expect(axisAutoscale.tickDecimals).to.be(3);
-
 
       var axisFixedscale = ctx.plotOptions.yaxes[1];
       expect(axisFixedscale.min).to.be(0.05);
@@ -148,8 +146,6 @@ describe('grafanaGraph', function() {
       expect(axisFixedscale.ticks.length).to.be(5);
       expect(axisFixedscale.ticks[0]).to.be(0.1);
       expect(axisFixedscale.ticks[4]).to.be(1000);
-      expect(axisFixedscale.tickDecimals).to.be(1);
-
     });
   });
 
@@ -172,7 +168,6 @@ describe('grafanaGraph', function() {
       expect(axisAutoscale.ticks.length).to.be(2);
       expect(axisAutoscale.ticks[0]).to.be(1);
       expect(axisAutoscale.ticks[1]).to.be(2);
-      expect(axisAutoscale.tickDecimals).to.be(undefined);
     });
   });
 
@@ -189,7 +184,7 @@ describe('grafanaGraph', function() {
       data[0].yaxis = 1;
     });
 
-    it('should set min to 0.1 and add a tick for 0.1 and tickDecimals to be 0', function() {
+    it('should set min to 0.1 and add a tick for 0.1', function() {
       var axisAutoscale = ctx.plotOptions.yaxes[0];
       expect(axisAutoscale.transform(100)).to.be(2);
       expect(axisAutoscale.inverseTransform(-3)).to.be(0.001);
@@ -198,7 +193,6 @@ describe('grafanaGraph', function() {
       expect(axisAutoscale.ticks.length).to.be(6);
       expect(axisAutoscale.ticks[0]).to.be(0.1);
       expect(axisAutoscale.ticks[5]).to.be(10000);
-      expect(axisAutoscale.tickDecimals).to.be(0);
     });
   });
 
@@ -222,7 +216,6 @@ describe('grafanaGraph', function() {
       expect(axisAutoscale.ticks[0]).to.be(0.1);
       expect(axisAutoscale.ticks[7]).to.be(262144);
       expect(axisAutoscale.max).to.be(262144);
-      expect(axisAutoscale.tickDecimals).to.be(0);
     });
 
     it('should set axis max to be max tick value', function() {