Revert "remove discount banner from track selection"

[MatthewPiatetsky]

Reverts edx/edx-platform#22285

[edx-status-bot]

Your PR has finished running tests. There were no failures.

[arch-bom-gocd-alerts]

📣 💥 Heads-up: You must either rebase onto master or merge master into your branch to avoid breaking the build.

We recently removed diff-quality and introduced lint-amnesty. This means that the automated quality check that has run on your branch doesn't work the same way it will on master. If you have introduced any quality failures, they might pass on the PR but then break the build on master.

This branch has been detected to not have commit 2e335653 as an ancestor. Here's how to see for yourself:

git merge-base --is-ancestor 2e335653 revert-22285-REV-1008 && echo "You're all set" || echo "Please rebase onto master or merge master to your branch"

If you have any questions, please reach out to the Architecture team (either #edx-shared-architecture on Open edX Slack or #architecture on edX internal).