Pages templates on the new project templates menu

What does this MR do?

Ports gitlab-org/gitlab-ce!24906 to EE

Adds templates for the 5 most popular Pages templates to the new project menu. This does not add unique icons for the templates because that turned out more complicated than expected, and this feature is valuable without them. Created https://gitlab.com/gitlab-org/gitlab-ce/issues/57040 for adding unique icons later.

https://gitlab.com/gitlab-org/gitlab-ce/issues/56986 is sort of a general spin-off issue to investigate if vendoring the templates in the repo is the best idea, but since this is what we were doing before that's what I've continued with here.

Docs issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/56991

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/47857

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer