Even if writing an acknowledgement is the norm in such a kind of report, acknowledgements remain a kind of gesture, which should have no impact on a professional evaluation. If such gestures have to be performed for their own sake, they become pointless and worthless¹: If literally everybody is being acknowledged, being acknowledged isn’t worth anything. Thus for acknowledgement having any point, there must be at least a small chance of, e.g., an advisor not being acknowledged, if this person really does not deserve it.
So, if your advisor did everything to be not worthy of any acknowledgement (as it sounds like), the only reason to acknowledge him would be that he still has impact on your grade or career². Assuming that this isn’t the case, the jury should not ask you about this missing acknowledgement, as your relationship to your supervisor should (idealistically) not play into your evaluation. (I will come back to this in a moment.)
As for your defense (or interview with the jury), I second the already given advice: Avoid appearing to place blame on your supervisor, but focus on the facts instead. Depending on what the mode of the defense is, e.g., if you are mainly asked questions and do not have to freely report on big chunks, you might not even need to address the issues yourself, unless asked. If you are however asked, e.g., why you made some decision on your project and it was due to your advisor commanding this decision, clearly say so. This also applies to the acknowledgement: If you are asked why you did not include one, it is the jury who brings up this topic and not you, and you can thruthfully say that you felt that there was nothing to acknowledge – but never bring on this topic on your own.
Another thing that you should be prepared for: If your internship was sufficiently long, the jury might hold the opinion that it was your responsibility to report severe problems to the university, such that it could assign you a new internship position or similar. Whether this opinion is justified depends on several factors, such as how much time this would have wasted and how high the risk would have been that such a complaint would have backfired at you and so on.
Also, if it’s not too late for this: Talk to your student body. They better know your specific situation than we do and might have experience with similar cases. Also, they have the means to drastically reduce the chances that this company ever gets an intern from your university again (I assume that they keep a list of good and bad companies for such internships).
Finally, talk to the jury (or another appropriate person), after everything is over. They also will have means to drastically reduce the chances that this company ever gets an intern from your university again.
¹ And you might enter some euphemism treadmill which ends up in a special acknowledgement language which has nothing to do with actual language anymore, as it is the case for employment reference letters in my country.
² Be aware that there might be not-so-obvious ties between your advisor and members of your university.