revert: revert "fix: re-add runOnce property to CronJob (kelektiv#751)"

This reverts commit a61d8c9.

src/job.ts

@@ -21,10 +21,6 @@ export class CronJob<OC extends CronOnCompleteCommand | null = null, C = null> {
 		? CronOnCompleteCallback
 		: undefined;
 
-	get runOnce(): boolean {
-		return this.cronTime.realDate;
-	}
-
 	private _timeout?: NodeJS.Timeout;
 	private _callbacks: CronCallback<C, WithOnComplete<OC>>[] = [];
 
@@ -259,7 +255,7 @@ export class CronJob<OC extends CronOnCompleteCommand | null = null, C = null> {
 				this.running = false;
 
 				// start before calling back so the callbacks have the ability to stop the cron job
-				if (!this.runOnce) {
+				if (!this.cronTime.realDate) {
 					this.start();
 				}