[$30] should not be able to create New Discussion in Challenge Discussions parent category

[Oanh-and-only-Oanh]

When user selects "Challenge Discussions", list of challenges that user has access to should be displayed. However, user should NOT be able to create any New Topics at this page. Remove New Discussion button on this page.

[jmgasper]

Challenge https://www.topcoder.com/challenges/f1ef7d50-cf6d-4b57-84ee-fa6ca786ad31 has been created for this ticket.

This is an automated message for ghostar via Topcoder X

[jmgasper]

Challenge https://www.topcoder.com/challenges/f1ef7d50-cf6d-4b57-84ee-fa6ca786ad31 has been assigned to obog.

This is an automated message for ghostar via Topcoder X

[atelomycterus]

@jmgasper Please apply PR -topcoder-platform/forums-groups-plugin#61. Thanks!

Testing