This reverts commit d133bf84, reversing
changes made to 7981c029.

Spam checks are meant for content that could be indexed by search
engines. Confidential issues aren't indexed by search engines, so we
don't need to do spam checks for them.

We do need to check for spam when an issue changes from confidential to
public, even if nothing else changed.

Moves the related_branches method from Issue model
to RelatedBranchesService

These methods don't really need to be on the Issue model. Issue#related_branches
can also be moved to a service, but we can do that in a separate commit.

This commit does not change any behaviour; it just moves code around, renames
the service, and refactors the specs.

This removes all usage of soft removals except for the "pending delete"
system implemented for projects. This in turn simplifies all the query
plans of the models that used soft removals. Since we don't really use
soft removals for anything useful there's no point in keeping it around.

This _does_ mean that hard removals of issues (which only admins can do
if I'm not mistaken) can influence the "iid" values, but that code is
broken to begin with. More on this (and how to fix it) can be found in
https://gitlab.com/gitlab-org/gitlab-ce/issues/31114.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/37447

This throttles the number of UPDATE queries that can be triggered by
calling "touch" on a Note, Issue, or MergeRequest. For Note objects we
also take care of updating the associated "noteable" relation in a
smarter way than Rails does by default.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

This ensures the issues/MR cache of the sidebar is only updated when the
state or confidential flags changes, instead of changing this for every
update.

Every project page displays a navigation menu that in turn displays the
number of open issues and merge requests. This means that for every
project page we run two COUNT(*) queries, each taking up roughly 30
milliseconds on GitLab.com. By caching these numbers and refreshing them
whenever necessary we can reduce loading times of all these pages by up
to roughly 60 milliseconds.

The number of open issues does not include confidential issues. This is
a trade-off to keep the code simple and to ensure refreshing the data
only needs 2 COUNT(*) queries instead of 3. A downside is that if a
project only has 5 confidential issues the counter will be set to 0.

Because we now have 3 similar counting service classes the code
previously used in Projects::ForksCountService has mostly been moved to
Projects::CountService, which in turn is reused by the various service
classes.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/36622

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Remove superfluous lib: true, type: redis, service: true, models: true, services: true, no_db: true, api: true
Signed-off-by: Rémy Coutable <remy@rymai.me>