Limit trial status widget experiment participants to group owners

As part of # we need to limit the segment of eligible experiment participants to those that meet the following criteria:

• The Group’s root ancestor group is in an active trial (was previously checking just the Group itself)
• The user is an owner of the Group’s root ancestor group (added by this issue’s MR)
• The user is not a member of any other Group with a paid account (not needed as the widget will only show up in the sidebar of groups whose root ancestor group is currently in a trial)