Use request.CTX instead of *request.Context (#24877)

* Use request.CTX instead of *request.Context

* Fix tests

server/channels/jobs/schedulers_test.go

@@ -30,7 +30,7 @@ func (scheduler *MockScheduler) NextScheduleTime(cfg *model.Config, now time.Tim
 	return &nextTime
 }
 
-func (scheduler *MockScheduler) ScheduleJob(c *request.Context, cfg *model.Config, pendingJobs bool, lastSuccessfulJob *model.Job) (*model.Job, *model.AppError) {
+func (scheduler *MockScheduler) ScheduleJob(c request.CTX, cfg *model.Config, pendingJobs bool, lastSuccessfulJob *model.Job) (*model.Job, *model.AppError) {
 	return nil, nil
 }