These are not required because MySQL is not
supported anymore

This reverts commit 2c3c5b35.

Revisit this after https://gitlab.com/gitlab-org/gitlab-ce/issues/45441

Otherwise we'd only preload the ancestors that would fit the
page. That way, when a search result was on the first page, but the
ancestor didn't fit the page anymore. We would not have the preloaded
ancestor when rendering the hierarchy.

When a project is shared with a group, it should not be included as a
descendant on the group dashboard.

By preloading the count of members, projects and subgroups of a group,
we don't need to query them later.

We also preload the entire hierarchy for a search result and include
the counts so we don't need to query for them again

When finding children for a group