Ohng, there are a lot of considerations when deciding whether to be an egg donor. The first and foremost to me would be - have you had children? I started trying to conceive at age 32, well before I had a Crohn's diagnosis, and it turned out that my ovaries were quite resistant to stimulation. While I had no specific diagnosis, I have come to believe (16 years later) that my Crohn's disease was already active and affecting my endocrine system.
If you are under age 30 and have had children, perhaps your ovulatory function is great and this is not a worry for you or the intended recipient.
Secondly, I have done 7 IVF cycles (also, before I had any idea that I had IBD). When you are stimulated to produce multiple eggs for the donation, your ovaries will get large and very, very tender. It may happen that the prostaglandins released during egg retrieval will irritate your bowel. You don't say what kind of surgery you had, but if there is any scarring in the pelvis this could make retrieval more difficult. You should consult with the reproductive endocrinologist about this.
During my IVF cycles, my bowel function was no better or worse than before. My acute symptoms of IBD did not begin until after the birth of my first daughter, so I cannot really address your main question about whether this procedure will be bad for your Crohn's.