feat(@schematics/angular): replace deprecated TestBed.get with TestBed.inject

Relates to angular/angular#32200

Author: alan-agius4

packages/schematics/angular/service/files/__name@dasherize@if-flat__/__name@dasherize__.service.spec.ts.template

@@ -7,7 +7,7 @@ describe('<%= classify(name) %>Service', () => {
 
   beforeEach(() => {
     TestBed.configureTestingModule({});
-    service = TestBed.get(<%= classify(name) %>Service);
+    service = TestBed.inject(<%= classify(name) %>Service);
   });
 
   it('should be created', () => {