PADV-1034 -Modify redeem Enterprise coupon page.

[Squirrel18]

Description:

This PR changes the redeem Enterprise coupon page per client requirements:

• Increase the number of courses to be displayed to 10.
• Change the introductory language.
• Remove unnecessary text.

Screenshots:

Before:

After:

How to test?

• Configure enterprise: https://open-edx-enterprise-service-documentation.readthedocs.io/en/latest/getting_started.html
• Set up an Enterprise customer.
• Set up an Enterprise catalogue.
• Configure Discovery service and run the metadata refresh command: https://edx-discovery.readthedocs.io/en/latest/quickstart.html
• Create an enterprise coupon and assign a catalogue to it: ECOMMERCE-HOST/enterprise/coupons
• Compile static files: make static (inside the ecommerce shell)
• Go to the redeem coupon page: ECOMMERCE-HOST/coupons/offer/?code=Enterprise coupon code
• Check that the changes have been applied.

Note:

These changes have been added here because .js files cannot be overwritten using themes and these changes apply to all sites.

Reviewers:

• @alexjmpb