No witnesses (officers, etc) are required to appear at an arraignment. The next court date may be a pretrial or docket sounding, and they are not required to appear at that court date either. The only court dates officers are required to appear for involve motions and trial dates. I would not count on an officer failing to appear for trial, that rarely happens. However, if the officer does not appear for trial, THEN the state will enter a nolle pros. I wouldn't hold my breath for that, hire an attorney, there are plenty of ways to get a possession of cannabis / marijuana dropped without hoping for a failure to appear.
In Miami, they/we do not have calendar call/soundings anymore on non-dui misdemeanors...meaning, your next hearing will be a trial. If the officer(s) fail(s) to appear and/or does not bring the evidence to court without a reasonable excuse, the case will likely be nolle prossed. This is likely something you can handle yourself but it doesn't hurt to have an attorney review your case, especially if there are any issues regarding your stop/seizure and search or whether you were in actual or constructive possession.
As stated above, the officer(s)' failure to appear at you arraignment is irrelevant.
The police and witnesses in general are not required to appear at the arraignment. Since it sounds like the court entered a not guilty plea on your behalf the next step will be a pretrial conference. No witnesses are required to appear at that hearing either. That will be a meeting between the prosecutor and either you or your attorney to try to resolve or settle the case. If the case can't be resolved then it will be placed on the court's trial docket. When the case is finally going to go to trial then witnesses will have to appear. Lastly, understand that police officers usually always show-up to court when told to do so; in many jurisdictions if the time of trial is outside of their normal work-shift hours then actually get overtime for coming to court. If you don't like the plea bargain they are offering you hire an attorney to assist you.