clarify when database.yml needs to be updated

Clarify that database.yml should be updated if you are running a MySQL Database. Remove wording that de-emphasises importance of update.
stop gitlab before mysql optimizations, run checks

Update MySQL optimizations to reflect doing updates after GitLab has already been started back up.
actually give command necessary to update unicorn

Give command to update unicorn.rb rather than just say you need to do it.
stop gitlab before backup

Stopping gitlab before backup ensures that backup has everything before upgrade incase something goes wrong. Also remove extra cd.
stop gitlab before backup
add missing configure Redis to use sockets

Add details from 7.2-to-7.3.md. Replaces https://github.com/gitlabhq/gitlabhq/pull/8047.
add optimizations for mysql to 6.x->7.4 guide

Add mysql optimizations from 7.3-to-7.4.md.
Ask the wiki repo, not Gollum, if it's empty

We need to skip empty repositories when creating a backup. Before this
change, we were asking gollum-lib if the wiki contains any _pages_. Now
we ask gitlab_git if the repository contains _files_. This should
resolve gollum_lib Grit timeouts in the backup script.
Fix group user removal from admin area

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Add tests for remove group member feature in admin area

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Prevent redeclaration of LDAP strategy
Default the LDAP server label to LDAP
Merge branch 'fixes-from-master' into '7-4-stable'

Fixes from master

It includes:

* https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1193
* https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1196
* https://dev.gitlab.org/gitlab/gitlabhq/merge_requests/1195

See merge request !1198
Use :message key, not :error for File::Service.
Merge pull request #8072 from bbodenmiller/patch-12

[7.4 rc fix] [doc] add optimizations for mysql to 6.x->7.4 guide
Merge pull request #8071 from bbodenmiller/patch-7

[7.4 rc fix] [doc] add missing configure Redis to use sockets
Merge pull request #8070 from bbodenmiller/patch-22

[7.4 rc fix] [doc] stop gitlab before backup
Merge pull request #8067 from bbodenmiller/patch-19

[7.4 rc fix] [doc] actually give command necessary to update unicorn
Merge pull request #8066 from bbodenmiller/patch-18

[7.4 rc fix] [doc] stop gitlab before mysql optimizations, run checks
Merge pull request #8065 from bbodenmiller/patch-17

[7.4 rc fix] [doc] clarify when database.yml needs to be updated