Fix cron disabled flag

[d-lukutin]

PR Checklist

Please check if your PR fulfills the following requirements:

• [ X] The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• [ X] Tests for the changes have been added (for bug fixes / features)
• [ X] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ X] Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Doesn't create a job.

Issue Number: N/A

What is the new behavior?

Creates a disabled job that can be enabled later.

Does this PR introduce a breaking change?

• [ X] Yes
• No

Other information

...

[kamilmysliwiec]

What would be the use case for enabling the explicitly disabled CRON job?

[d-lukutin]

What would be the use case for enabling the explicitly disabled CRON job?

export class Job1Service {
    @Cron('* * * * * *', {
        name: Job1Service.name,
        disabled: true
    })
    async job() {
        ...
    }
}

...

export class JobXService {
    @Cron('* * * * * *', {
        name: JobXService.name,
        disabled: true
    })
    async job() {
        ...
    }
}

export class JobsEnabledService {
     constructor(
         private readonly configurationService: ConfigurationService,
         private readonly schedulerRegistry: SchedulerRegistry
     ) {}

    @Cron('*/10 * * * * *', {
        name: JobsEnabledService.name
    })
    async job() {
        if(awaitn this.configurationService.enabled()) {
            this.schedulerRegistry.getCronJobs()
                .forEach((job, jobName) => {
                    if (jobName !== EnableWorkJobService.name && !job.running) job.start();
                });
        }
        else {
            this.schedulerRegistry.getCronJobs()
                .forEach((job, jobName) => {
                    if (jobName !== EnableWorkJobService.name && job.running) job.stop();
                });
        }
    }
}

[kamilmysliwiec]

LGTM