The githost.log name was often confused with GitHost.io. Rename this to
git_json.log to make it clear it's coming from Git and that it's JSON
data.

This MR adds new application setting to network section
`allow_local_requests_from_system_hooks`. Prior to this change
system hooks were allowed to do local network requests by default
and we are adding an ability for admins to control it.

Creates a new item in help dropdown to show configured support page link

We dropped MySQL support and a lot of mysql specific code has been
removed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/29608.

This comes in from the other direction and removes any `if postgresql?`
branches.

Using the sed script from
https://gitlab.com/gitlab-org/gitlab-ce/issues/59758

It seems that we missed the backward compatibility support
for profiles in the existing folder.

This commit also fixes some specs to be idempotent
and work in a temporary directory which not always
seems to be the case.

This commit also brings the profile_spec.rb which seems
to be missing.

Add a group setting to allow Maintainers to create sub-groups

See merge request gitlab-org/gitlab-ce!29718