Will Taking an AP Test Give Me Possible Elective Credit in Another Subject?

Background:
I am a senior highschool student in So Cal. I hav taking about 11 ap classes so far including this year, and I plan to major in Aero-space engineering or Theoretical Physics. I am super good at math, undoubtedly the best mathematician in my school right now. This is because our school offers up to AP Calculus BC, (so basically up to Calc 2 in college). I have been going to my local community college and taking college classes there to get ahead, and by the end of senior year, I wll have finished Calc 3. Now, I am talking about UC’s ONLY. I made sure the classes I took were transferable credits, so according to the UC Ap Credit website, I am eligible to skip the first 2 classes of calc at the university. I got an A in Calc 1 and a B in Calc 2, which is basically a 5 in AP Calc AB and a 4 in AP Calc BC; this allows me recieve my credits for both classes (I have already stated all of this in my UC application). I am pretty sure I will be able to recieve credits for the 3rd Calc class, cause I’m sure I’ll pass Calc 3 at my Community College.

Problem:
Now, I thought to my self, obvoiusly I do not need to take the AP Calc BC test coming becasue I should already recive my credit for those classes because I already finished them and I am going extra. I went to go talk to my highschool counsler (wasn’t able to get in touch with my communinty college cousler) about my situatoin and she told me to go take the test. She told me that apparently, if you take AP test and pass, but you already have passed that specific class, you will be able to reiveve elective credit for how I score on the upcoming AP exam!

Questions:
Would UC schools really give credit for classes that you didn’t even take? I there any validity in what my counsler said? Do you guys think there will be any point in taking the upcoimg AP Calc BC exam?