Merge branch 'bdenkovych-rename-enterprise-users-service-class-and-mailer' into 'master'

Rename `Groups::EnterpriseUsers::CreateService` class and its email

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/125135



Merged-by: Roy Zwambag <rzwambag@gitlab.com>
Approved-by: Jessie Young <jessieyoung@gitlab.com>
Approved-by: Roy Zwambag <rzwambag@gitlab.com>
Co-authored-by: Bogdan Denkovych <bdenkovych@gitlab.com>