Update billing page trial CTAs

Problem

Currently, we have two CTAs on both the group and personal billing pages and the CTAs direct the user to the old trial flow.

Solution

We should implement two fixes on both the group billing page and the personal billing page.

Fix 1: We should remove the top trial banner from both the group and personal billing pages: https://gitlab.com/profile/billings and https://gitlab.com/groups/(group-name-goes here)/-/billings

Fix 2: The Gold trial CTA on both the group billing page and the personal billing page should direct users into the new trial signup flow. The new URL that should be used is as follows: https://gitlab.com/-/trial_registrations/new