CE backport of "Configure the number of ES shards and replicas"

See merge request gitlab-org/gitlab-ce!28329

```
StandardError: An error has occurred, all later migrations canceled:

Mysql2::Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'system = true AND note LIKE '\_%\_'' at line 1: UPDATE notes SET note = trim(both '_' from note) WHERE system = true AND note LIKE '\_%\_'
```

CE backport of merge request blocks - backend MVC

See merge request gitlab-org/gitlab-ce!27323

Udpated user_edit_profile_spec with time preferences

Minor update form fields

Issues and merge requests imported from GitHub are having state_id
set to null. This fixes the GitHub project importer and schedule
migrations to fix state_id.

Add env_var and file as supported types for CI variables. Variables of
type file expose to users existing gitlab-runner behaviour - save
variable value into a temp file and set the path to this file in an ENV
var named after the variable key.

Resolves https://gitlab.com/gitlab-org/gitlab-ce/issues/46806.

This database table and AR model is going to be used for
the merge train feature.