FAL-78 Fix the MKTG_URL_LINK_MAP override

Created by: s0b0lev

This PR is about resolving conflicts for the MKTG_URL_LINK_MAP configuration.

Description

The issue with the previous implementation happens for juniper.3 release.

• https://github.com/open-craft/edx-platform/blob/opencraft-release/juniper.3/common/djangoapps/edxmako/shortcuts.py#L93

For testing master branch was used.

• https://github.com/edx/edx-platform/blob/master/common/djangoapps/edxmako/shortcuts.py#L96

This PR was tested on both environments and work fine for master and juniper.3 .

Testing instruction:

• Follow testing instruction in the ticket details

Authors notes:

• Included API client updates
• Instead of injecting the full list into MKTG_URL_LINK_MAP - this code will add only disabled pages