Remove hardcoded path for admin.secret file and use the directory defined in configuration

What does this MR do?

This MR replace the hardcoded path for gitlab-pages folder.
If the gitlab-pages dir configuration is not the default one the chef script fail during reconfigure and the gitlab-pages service fail to start
The page folder should not be hardcoded and should use the configuration defined in the gitlab.rb.

Error:

 * template[/var/opt/gitlab/gitlab-pages/admin.secret] action create
    * Parent directory /var/opt/gitlab/gitlab-pages does not exist.
    ================================================================================
    Error executing action `create` on resource 'template[/var/opt/gitlab/gitlab-pages/admin.secret]'
    ================================================================================

    Chef::Exceptions::EnclosingDirectoryDoesNotExist
    ------------------------------------------------
    Parent directory /var/opt/gitlab/gitlab-pages does not exist.

    Resource Declaration:
    ---------------------
    # In /opt/gitlab/embedded/cookbooks/cache/cookbooks/gitlab/recipes/gitlab-pages.rb

     41: template admin_secret_path do
     42:   source "secret_token.erb"
     43:   owner 'root'
     44:   group account_helper.gitlab_group
     45:   mode "0640"
     46:   variables(secret_token: node['gitlab']['gitlab-pages']['admin_secret_token'])
     47:   notifies :restart, "service[gitlab-pages]"
     48: end
     49:

Running handlers:
There was an error running gitlab-ctl reconfigure:

template[/var/opt/gitlab/gitlab-pages/admin.secret] (gitlab::gitlab-pages line 41) had an error: Chef::Exceptions::EnclosingDirectoryDoesNotExist: Parent directory /var/opt/gitlab/gitlab-pages does not exist.

Checklist

• MR targeting master branch
• MR has a green pipeline on GitLab.com

Reviewer Checklist

In addition to above, reviewer must:

• Pipeline is green on dev.gitlab.org if the change is not touching documentation or internal cookbooks

References

Close #3639 (closed)