[PM-16262] Make getEnvironment observable and use it in SdkService (#12501)

* feat: re-implement getEnvironment as an observable

* feat: deprecate `getEnvironment`

* fix: use correct environment function in SdkService

* fix: test

libs/common/src/platform/services/sdk/default-sdk.service.spec.ts

@@ -56,6 +56,9 @@ describe("DefaultSdkService", () => {
       const userId = "user-id" as UserId;
 
       beforeEach(() => {
+        environmentService.getEnvironment$
+          .calledWith(userId)
+          .mockReturnValue(new BehaviorSubject(mock<Environment>()));
         accountService.accounts$ = of({
           [userId]: { email: "email", emailVerified: true, name: "name" } as AccountInfo,
         });