fix(server): make system config core singleton (#4392)

* make system config core singleton

* refactor

* fix tests

* chore: fix tests

---------

Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>

server/src/domain/job/job.service.spec.ts

@@ -223,8 +223,7 @@ describe(JobService.name, () => {
     it('should subscribe to config changes', async () => {
       await sut.registerHandlers(makeMockHandlers(false));
 
-      const configCore = new SystemConfigCore(newSystemConfigRepositoryMock());
-      configCore.config$.next({
+      SystemConfigCore.create(newSystemConfigRepositoryMock(false)).config$.next({
         job: {
           [QueueName.BACKGROUND_TASK]: { concurrency: 10 },
           [QueueName.CLIP_ENCODING]: { concurrency: 10 },

server/src/domain/job/job.service.ts

@@ -21,7 +21,7 @@ export class JobService {
     @Inject(ISystemConfigRepository) configRepository: ISystemConfigRepository,
     @Inject(IPersonRepository) private personRepository: IPersonRepository,
   ) {
-    this.configCore = new SystemConfigCore(configRepository);
+    this.configCore = SystemConfigCore.create(configRepository);
   }
 
   async handleCommand(queueName: QueueName, dto: JobCommandDto): Promise<JobStatusDto> {