test(material/select): attempt to reduce test flakes (#25646)

Tries to reduce the amount of flakes we've been seeing in the select tests by getting one of the slower tests to run faster.

Author: crisbeto

src/material/legacy-select/select.spec.ts

@@ -110,9 +110,7 @@ describe('MatSelect', () => {
       ],
     }).compileComponents();
 
-    inject([OverlayContainer], (oc: OverlayContainer) => {
-      overlayContainerElement = oc.getContainerElement();
-    })();
+    overlayContainerElement = TestBed.inject(OverlayContainer).getContainerElement();
   }
 
   describe('core', () => {
@@ -6002,7 +6000,7 @@ class SelectWithNgIfAndLabel {
   `,
 })
 class MultiSelectWithLotsOfOptions {
-  items = new Array(1000).fill(0).map((_, i) => i);
+  items = new Array(100).fill(0).map((_, i) => i);
   value: number[] = [];
 
   checkAll() {

src/material/select/select.spec.ts

@@ -108,9 +108,7 @@ describe('MDC-based MatSelect', () => {
       ],
     }).compileComponents();
 
-    inject([OverlayContainer], (oc: OverlayContainer) => {
-      overlayContainerElement = oc.getContainerElement();
-    })();
+    overlayContainerElement = TestBed.inject(OverlayContainer).getContainerElement();
   }
 
   describe('core', () => {
@@ -5021,7 +5019,7 @@ class SelectWithNgIfAndLabel {
   `,
 })
 class MultiSelectWithLotsOfOptions {
-  items = new Array(1000).fill(0).map((_, i) => i);
+  items = new Array(100).fill(0).map((_, i) => i);
   value: number[] = [];
 
   checkAll() {