Add informational tooltips to AI Impact Analytics overview tiles

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/163989



Merged-by: Ezekiel Kigbo <3397881-ekigbo@users.noreply.gitlab.com>
Approved-by: Alex Pennells <apennells@gitlab.com>
Approved-by: Libor Vanc <5022246-lvanc@users.noreply.gitlab.com>
Approved-by: Lorena Ciutacu <lciutacu@gitlab.com>
Approved-by: Ezekiel Kigbo <3397881-ekigbo@users.noreply.gitlab.com>
Reviewed-by: Ezekiel Kigbo <3397881-ekigbo@users.noreply.gitlab.com>
Reviewed-by: Alex Pennells <apennells@gitlab.com>
Reviewed-by: Rudy Crespo <rcrespo@gitlab.com>
Co-authored-by: Rudy Crespo <rcrespo@gitlab.com>