Closes gitaly#929

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

See https://github.com/rails/rails/pull/24658#issuecomment-212651965

Closes gitaly#907

Closes gitaly#903

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

Up until version 2.0.3 redis-rack included a "rake" binary that would
overwrite/hijack the one provided by Rake itself. Unfortunately the
binary provided by redis-rack would produce errors in many cases. See
https://github.com/redis-store/redis-rack/pull/34 for more info.

Closes gitaly#825

Minor changes: https://github.com/mperham/sidekiq/blob/master/Changes.md

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

Uses `list_commits_by_oid` on the CommitService, to request the needed
commits for pipelines. These commits are needed to display the user that
created the commit and the commit title.

This includes fixes for tests failing that depended on the commit
being `nil`. However, now these are batch loaded, this doesn't happen
anymore and the commits are an instance of BatchLoader.

I've followed the [upgrade guide](https://github.com/thoughtbot/factory_bot/blob/4-9-0-stable/UPGRADE_FROM_FACTORY_GIRL.md

) and ran these two commands:

```
grep -e FactoryGirl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|FactoryGirl|FactoryBot|"
grep -e factory_girl **/*.rake **/*.rb -s -l | xargs sed -i "" "s|factory_girl|factory_bot|"
```

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

- Added an ActiveSupport (using Rails.cache) caching adapter
- Overview of the new features can be found at https://johnnunemaker.com/flippin-features-at-runtime/
- Full Changelog can be found at https://github.com/jnunemaker/flipper/blob/v0.11.0/Changelog.md



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

Closes gitaly#808

Only the Gemfile.lock was updated before.

+ change string concatenation to help with GC pressure.
+ fix metric producing incompatible label sets

Closes gitaly#780

Closes gitaly#737

Changes since 4.2.8:

- [No change in ActionMailer](https://github.com/rails/rails/blob/v4.2.10/actionmailer/CHANGELOG.md)
- [1 change and 1 regression fix in ActionPack](https://github.com/rails/rails/blob/v4.2.10/actionpack/CHANGELOG.md)
- [No change in ActiveModel](https://github.com/rails/rails/blob/v4.2.10/activemodel/CHANGELOG.md)
- [7 fixes in ActiveRecord](https://github.com/rails/rails/blob/v4.2.10/activerecord/CHANGELOG.md)
- [5 fixes in ActiveSupport](https://github.com/rails/rails/blob/v4.2.10/activesupport/CHANGELOG.md)
- [No change in Railties](https://github.com/rails/rails/blob/v4.2.10/railties/CHANGELOG.md

)

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

See https://gitlab.com/gitlab-org/gitlab-ce/issues/40690 and
https://github.com/mbleigh/seed-fu/issues/123

 for details.

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

[ci skip]