Replace invite banner button with modal trigger

What does this MR do?

Changes the button on the "Invite your colleagues" banner to open the Invite Members modal, instead of being a link taking them to the Members page.

Related to "Invite your colleagues" banner successful experiment cleanup: https://gitlab.com/gitlab-org/gitlab/-/issues/323106

Related to !59203 (merged)

Related to gitlab-ui!2144 (merged)

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/247208

• To test:

1. Create a new group as an admin or owner, with only 1 member (yourself) in that group.
2. Visit group overview page again, or reload (the banner will not display if the "Group name created" flash message is there)

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

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