gitlab: Sync gitlab-parameters.cfg to upstream

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.

software/gitlab/gitlab-parameters.cfg

@@ -6,7 +6,7 @@
 #
 # TODO better autogenerate from ^^^ (?)
 #
-# (last updated for omnibus-gitlab 8.7.9+ce.1-0-gf589ad7)
+# (last updated for omnibus-gitlab 8.8.9+ce.0-g25376053)
 
 [gitlab-parameters]
 configuration.external_url              = http://lab.example.com

software/gitlab/software.cfg

@@ -232,7 +232,7 @@ md5sum  = eb1230fee50067924ba89f4dc6e82fa9
 
 [gitlab-parameters.cfg]
 <= download-file
-md5sum  = 3edd435a984b51b94539ea1d4f1b3994
+md5sum  = a74670934ec0190cc212d1f3468c11ed
 
 [gitlab-shell-config.yml.in]
 <= download-template