fix tests and make registration in legacy platform possible

src/legacy/ui/public/new_platform/new_platform.karma_mock.js

@@ -131,6 +131,9 @@ export const npSetup = {
       featureCatalogue: {
         register: sinon.fake(),
       },
+      environment: {
+        update: sinon.fake(),
+      },
     },
   },
 };

src/plugins/home/public/services/environment/environment.test.ts

@@ -41,14 +41,5 @@ describe('EnvironmentService', () => {
       setup.update({ ml: false, apmUi: true });
       expect(service.start().get()).toEqual({ ml: false, cloud: true, apmUi: true });
     });
-
-    test('fails if trying to update state after setup phase', () => {
-      const service = new EnvironmentService();
-      const setup = service.setup();
-      service.start();
-      expect(() => {
-        setup.update({ ml: true });
-      }).toThrow();
-    });
   });
 });

src/plugins/home/public/services/environment/environment.ts

@@ -34,7 +34,6 @@ export interface Environment {
 }
 
 export class EnvironmentService {
-  private frozen = false;
   private environment = {
     cloud: false,
     apmUi: false,
@@ -51,19 +50,12 @@ export class EnvironmentService {
        * @param update
        */
       update: (update: Partial<Environment>) => {
-        if (this.frozen) {
-          throw new Error(
-            'Environment already frozen, did you try to change the environment in the start phase?'
-          );
-        }
         this.environment = Object.assign({}, this.environment, update);
       },
     };
   }
 
   public start() {
-    this.frozen = true;
-    Object.freeze(this.environment);
     return {
       /**
        * Retrieve the current environment home is running in. This API is only intended for internal