Deprecate www-gitlab-com2.7 image tag

As with gitlab-com/www-gitlab-com!78850 (merged) and gitlab-com/www-gitlab-com!79862 (merged), we completely upgraded Ruby from 2.7 to 3.0, we can safely registry.gitlab.com/gitlab-org/gitlab-build-images:deprecate www-gitlab-com-2.7 tag. This MR does not mean the tag will not available after getting this merged until it is deleted on another issue.

Signed-off-by: Takuya Noguchi takninnovationresearch@gmail.com