In prevision for gitlab-backup restore to be done in a script. In fact, it requires `sed` command to be available.
We have to add /bin to the PATH as `which sed` returns `/bin/sed`.

  - git-clone and build git-backup sources
  - add a cron job doing `gitlab-backup-pull` every 4 hours by default
  - add instance parameter to change backup frequency
  - add xnice for using less resources while backuping
  - add lock to avoid concurrent calls of backup script
  - add a specific software type `gitlab-export` doing all this instead of in
    `default`; this can be changed in Services > parameters (kirr's changes)

`coreutils`, `grep` and `tar` components are used by `gitlab-backup-pull`
script, as it is called from a cron and the PATH has to include these
binaries paths

This is needed until the patch regarding `pidfile` in wrapper.py
is added to SlapOS cookbook.

The 'pidfile' parameter is passed to 'createWrapper' method in order to
avoid concurrent calls.

Update GitLab software to

    - gitlab-ce 8.8.9 + NXD patches

    - gitlab-shell stays at 2.7.2 + 1 patch to remove unneeded hooks.old in *.git
      because gitlab-ce 8.7.x sticks to this version (i.e. no shell upgrade for
      gitlab 8.7 -> 8.8)

    - gitlab-workhorse stays at 0.7.1 + NXD patches because gitlab-ce 8.8.x
      sticks to this version (i.e. no workhorse upgrade for gitlab 8.7 -> 8.8)

This only updates software and begins SR update to 8.8 - for now gitlab
instance starts using gitlab-ce appropriate version.

it is no longer possible to use http:/ as curl now expect a hostname to be
given, see curl issue https://github.com/curl/curl/issues/936

Like for af0c5b11

    $ git diff 8-7-stable 8-8-stable --
            files/gitlab-cookbooks/gitlab/templates/default/sv-sidekiq-run.erb

is empty.

Like for 61177775.

I've manually reviewed

    git diff 8-7-stable 8-8-stable -- files/gitlab-config-template/gitlab.rb.template \
                                      files/gitlab-cookbooks/gitlab/attributes/default.rb

on omnibus-gitlab repository.

There are only changes on postgresql and registry options, which are not relevant for us.

Do not use container_registry and registry_* options

This does almost(*) only pure merge. We will slaposify / adjust config
and corresponding md5sum in the following patches.

(*) condition on smtp_authentication was applied by hand on smtp_settings.rb.in

In the case of hellorina SR, the following section generated invalid command:

[proxy]
command-line = {{ python_location }}/bin/python2.7 {{ rina_proxy }} ${server:instance-guid} ${:ipv6} ${:port}
...

This value can be used as a unique identifier within the cloud.
It was already available for the requesting partition ('request' recipe).

/reviewed-on nexedi/slapos!101