Add automated test for "User membership in the profile"

The manual test is here: User membership in the profile

Existing automated coverage

• UserProfileIT#verifyGroupTab: Opens the profile Groups tab of a fresh user and asserts it lists only XWikiAllGroup with its link.
• DefaultGroupManagerTest#getGroupsWhenOneDirectAndOneRecursive: Unit test (mocks): the group manager returns groups of groups.
• DefaultGroupManagerTest#getGroupsWhenOneDirectOnRecursiveOnSeveralWikis: Unit test (mocks): the group manager returns direct and nested groups on several wikis.

Missing automated coverage

• Create a global user and add it to 2 groups on the main wiki, one of them member of a parent group
• Create a subwiki allowing global users and add the user to a group there
• As admin, from the main wiki, open the user's profile > Groups and assert the direct groups, the parent group and the subwiki group are all listed
• Log in as the user, open profile > Groups and assert the same list

Suggested location: xwiki-platform-core/xwiki-platform-user/xwiki-platform-user-profile/xwiki-platform-user-profile-test/xwiki-platform-user-profile-test-docker/src/test/it/org/xwiki/user/test/ui/UserProfileIT.java

Found by comparing the XWiki 18.4.4 manual test runs against the automated tests on master (a0055f10a1a).