Update "AI-powered" terminology to "AI-native", to align with TW approved language

The following discussion from !188522 (merged) should be addressed:

• @julie_huang started a discussion: (+9 comments)

  @timnoah are you able to review for UX please?

  I'm also wondering if we should review the copy for the jump-off card? What do you think of something like "GitLab Duo Self-Hosted" for the header instead? CC: @jglassman1