refactor(benchpress): remove two mutable exports from largetable/util.ts (#32425)

Mutable exports, i.e. using this pattern

```
export let x = 0;
export function f() {
  x += 1;
}
```

is problematic to transpile to CommonJS and Goog.module systems, we are
working on banning it google internal codebase.

The workaround is adding an explcit getter function.

PR Close #32425

modules/benchmarks/src/largetable/util.ts

@@ -13,8 +13,8 @@ export class TableCell {
 }
 
 let tableCreateCount: number;
-export let maxRow: number;
-export let maxCol: number;
+let maxRow: number;
+let maxCol: number;
 let numberData: TableCell[][];
 let charData: TableCell[][];
 

modules/benchmarks/src/tree/ng2_static/tree.ts

@@ -9,7 +9,7 @@
 import {Component, Input, NgModule} from '@angular/core';
 import {BrowserModule, DomSanitizer, SafeStyle} from '@angular/platform-browser';
 
-import {TreeNode, emptyTree, maxDepth} from '../util';
+import {TreeNode, emptyTree, getMaxDepth} from '../util';
 
 let trustedEmptyColor: SafeStyle;
 let trustedGreyColor: SafeStyle;
@@ -40,8 +40,8 @@ export class RootTreeComponent {
 
 function createModule(): any {
   const components: any[] = [RootTreeComponent];
-  for (let i = 0; i <= maxDepth; i++) {
-    components.push(createTreeComponent(i, i === maxDepth));
+  for (let i = 0; i <= getMaxDepth(); i++) {
+    components.push(createTreeComponent(i, i === getMaxDepth()));
   }
 
   @NgModule({imports: [BrowserModule], bootstrap: [RootTreeComponent], declarations: [components]})

modules/benchmarks/src/tree/util.ts

@@ -25,10 +25,14 @@ export class TreeNode {
 }
 
 let treeCreateCount: number;
-export let maxDepth: number;
+let maxDepth: number;
 let numberData: TreeNode;
 let charData: TreeNode;
 
+export function getMaxDepth() {
+  return maxDepth;
+}
+
 init();
 
 function init() {