[WIP] Fix feature flag loading issue on product pages

[ChristopherChudzicki]

What are the relevant tickets?

Closes https://github.com/mitodl/hq/issues/9317

Description (What does it do?)

This PR fixes an issue where the feature-flagged product pages would occasionally show 404, particularly on slow networks.

How can this be tested?

If you really want to see (A) the issue on main and (B) that this PR fixes it:

1. Prerequisites:
   • Learn <> MITxOnline integration set up
   • Posthog setup with product-course-page flag enabled
   • NODE_ENV=production in frontend.local.env (I find that page loads too slowly in dev mode, meaning that posthog always loads latest; the race condition is much more reproducible in production mode.)
2. On main:
   1. visit http://open.odl.local:8062/programs/<readable-id>
   2. enable network throttling (4G should be good enough) and reload the page. If you don't get 404, keep reloading, but I've found it very reproducible on 4G throttling in production mode.
3. Repeat Step 2 on this branch.

[pdpinch]

Will this close https://github.com/mitodl/hq/issues/9335 ?

[ChristopherChudzicki]

@pdpinch Yes.

[ChristopherChudzicki]

Closing in favor of #2720