Custom CACert are ignored for Elasticsearch global search
### Summary
Custom certs are not used in Gitlab with global search & lfs.
### Steps to reproduce
1. enable global search following https://docs.gitlab.com/ee/integration/elasticsearch.html with SSL elasticsearch endpoint
2. gitlab-rake gitlab:elastic:create_empty_index
### Example Project
n/a
### What is the current *bug* behavior?
Gitlab ignores my CA
1. add my ca /etc/gitlab/trusted-certs/myca.pem
2. run reconfigure
3. /opt/gitlab/embedded/ssl/certs/e385f43f.0 was create
```
curl --cacert /opt/gitlab/embedded/ssl/certs/cacert.pem https://myes.lan:9200
KO
curl --cacert /opt/gitlab/embedded/ssl/certs/e385f43f.0 https://myes.lan:9200
OK
```
4. gitlab-rake gitlab:elastic:create_empty_index
But I still got an error 500 with SSL Error
Now copy the content to cacert
```
cat /opt/gitlab/embedded/ssl/certs/e385f43f.0 >> /opt/gitlab/embedded/ssl/certs/cacert.pem
gitlab-ctl restart
```
Both works
```
curl --cacert /opt/gitlab/embedded/ssl/certs/cacert.pem https://myes.lan:9200
OK
curl --cacert /opt/gitlab/embedded/ssl/certs/e385f43f.0 https://myes.lan:9200
OK
```
Run
gitlab-rake gitlab:elastic:create_empty_index
OK
### What is the expected *correct* behavior?
Gitlab must allow my CA for any services from Gitlab using both cacert and myca CAs.
### Relevant logs and/or screenshots
Nothing in logs
### Output of checks
#### Results of GitLab environment info
<details>
<summary>Expand for output related to GitLab environment info</summary>
<pre>
$ sudo gitlab-rake gitlab:env:info
System information
System: RedHatEnterpriseServer 6.9
Proxy: no
Current User: git
Using RVM: no
Ruby Version: 2.3.7p456
Gem Version: 2.6.14
Bundler Version:1.13.7
Rake Version: 12.3.1
Redis Version: 3.2.11
Git Version: 2.16.4
Sidekiq Version:5.0.5
Go Version: unknown
GitLab information
Version: 10.8.3-ee
Revision: 3e7879a
Directory: /opt/gitlab/embedded/service/gitlab-rails
DB Adapter: postgresql
DB Version: 9.6.8
URL: https://xxxxxxxxxxxxxxxxxxxxxx
HTTP Clone URL: https://xxxxxxxxxxxxxxxxxxxxxx/some-group/some-project.git
SSH Clone URL: git@xxxxxxxxxxxxxxxxxxxxxx:some-group/some-project.git
Elasticsearch: yes
Geo: no
Using LDAP: yes
Using Omniauth: no
GitLab Shell
Version: 7.1.2
Repository storage paths:
- default: /var/opt/gitlab/git-data/repositories
Hooks: /opt/gitlab/embedded/service/gitlab-shell/hooks
Git: /opt/gitlab/embedded/bin/git
</pre>
</details>
#### Results of GitLab application Check
<details>
<summary>Expand for output related to the GitLab application check</summary>
<pre>
Checking GitLab Shell ...
GitLab Shell version >= 7.1.2 ? ... OK (7.1.2)
Repo base directory exists?
default... yes
Repo storage directories are symlinks?
default... no
Repo paths owned by git:root, or git:git?
default... yes
Repo paths access is drwxrws---?
default... yes
hooks directories in repos are links: ...
XXXX/YYYY ... ok
Redis version >= 2.8.0? ... yes
Ruby version >= 2.3.5 ? ... yes (2.3.7)
Git version >= 2.9.5 ? ... yes (2.16.4)
Git user has default SSH configuration? ... no
...
Active users: ... xxx
Elasticsearch version 5.1 - 5.5? ... no (5.6.9)
For more information see:
doc/integration/elasticsearch.md
</pre>
</details>
### Possible fixes
In reconfigure, may be append custom CAs to cacert or uses all CA configured for gitlab
issue