CLC-2442 Handle primary section enrollments with same course catalog ID
Many classes were not being shown correctly or were being skipped in GPA calculation. We're limited by source data issues, but this commit should fix the problems students have reported. Includes a couple of other fixes as well:
- Don't unnecessarily stringify waitlist position & section enrollment limit.
- Don't count unrecognized/unavailable transcript grades as an "A" letter grade in the GPA Calculator.
- Don't do the intensive JavaScript work to set up an Academics semester page unless the browser is actually going to the semester page.