Price card on course pages shouldn't link to checkout

[jkachel]

As noted in https://github.mit.edu/mitxonline/mitxonline-issues/issues/156 , the Price card should not link to the cart once a learner has an approved financial assistance record.

Steps to Reproduce

1. Apply for and approve a financial assistance request for a given learner.
2. Log in as that learner and navigate to the course the request was for.
3. Observe the Price card

Expected Behavior

The Price card should show the learner's adjusted price, but only that.

Actual Behavior

The price is a link to purchase the course. (This behavior is as designed - the request is to change it to not do that anymore.)

Related Issues

https://github.mit.edu/mitxonline/mitxonline-issues/issues/156 - "Price" Box Contents Behave Differently for Some Courses

If you're not on a course with financial assistance, the price never changes to a checkout link.

https://github.mit.edu/mitxonline/mitxonline-issues/issues/157 - "Price" box link-text for DEDP courses linking to checkout page for course sessions after their payment deadline

This is an actual bug - the Price link doesn't respect the currently selected date if there's more than one, or payment/enrollment deadlines - but if we don't make the Price link a checkout link, then this is also resolved.