ui: Default sort by Execution Count column for Statements

Before, default sorting was set to Latency column in
Statements page that was unintuitive.
Now it is sorted by Execution count column.

Release note (admin ui change): Change default sorting column on Statements
page to Execution Count

Release justification: bug fixes and low-risk updates to new functionality

pkg/ui/src/views/statements/statementsPage.spec.tsx

@@ -0,0 +1,34 @@
+// Copyright 2018 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+import React from "react";
+import { assert } from "chai";
+import { ReactWrapper } from "enzyme";
+
+import { connectedMount } from "src/test-utils";
+import StatementsPageConnected, {
+  StatementsPage,
+  StatementsPageProps,
+  StatementsPageState,
+} from "src/views/statements/statementsPage";
+
+describe("StatementsPage", () => {
+  describe("Statements table", () => {
+    it("sorts data by Execution Count DESC as default option", () => {
+      const rootWrapper = connectedMount(() => <StatementsPageConnected />);
+
+      const statementsPageWrapper: ReactWrapper<StatementsPageProps, StatementsPageState> = rootWrapper.find(StatementsPage).first();
+      const statementsPageInstance = statementsPageWrapper.instance();
+
+      assert.equal(statementsPageInstance.state.sortSetting.sortKey, 3);
+      assert.equal(statementsPageInstance.state.sortSetting.ascending, false);
+    });
+  });
+});

pkg/ui/src/views/statements/statementsPage.tsx

@@ -47,7 +47,7 @@ import "./statements.styl";
 
 type ICollectedStatementStatistics = protos.cockroach.server.serverpb.StatementsResponse.ICollectedStatementStatistics;
 
-interface StatementsPageProps {
+interface OwnProps {
   statements: AggregateStatistics[];
   statementsError: Error | null;
   apps: string[];
@@ -62,20 +62,22 @@ type PaginationSettings = {
   current: number;
 };
 
-interface StatementsPageState {
+export interface StatementsPageState {
   sortSetting: SortSetting;
   pagination: PaginationSettings;
   search?: string;
 }
 
-export class StatementsPage extends React.Component<StatementsPageProps & RouteComponentProps<any>, StatementsPageState> {
+export type StatementsPageProps = OwnProps & RouteComponentProps<any>;
+
+export class StatementsPage extends React.Component<StatementsPageProps, StatementsPageState> {
   activateDiagnosticsRef: React.RefObject<ActivateDiagnosticsModalRef>;
 
-  constructor(props: StatementsPageProps & RouteComponentProps<any>) {
+  constructor(props: StatementsPageProps) {
     super(props);
     const defaultState = {
       sortSetting: {
-        sortKey: 6, // Latency column is default for sorting
+        sortKey: 3, // Sort by Execution Count column as default option
         ascending: false,
       },
       pagination: {