Fix application_settings JOIN condition for CiBuildsProbe

After https://gitlab.com/gitlab-org/gitlab/-/merge_requests/29981, we cannot assume an application_settings
with ID=1 exists. But we know that there will only be one record in that table, so we can change the JOIN
condition to TRUE safely.

Fixes #71

Gemfile.lock

 PATH
   remote: .
   specs:
-    gitlab-exporter (7.0.5)
+    gitlab-exporter (7.0.6)
       connection_pool (~> 2.2.1)
       pg (~> 1.1)
       quantile (~> 0.2.0)

lib/gitlab_exporter/database/ci_builds.rb

@@ -21,8 +21,7 @@ module GitLab
               ON namespaces.id = projects.namespace_id
             LEFT JOIN namespace_statistics
               ON namespace_statistics.namespace_id = namespaces.id
-            JOIN application_settings
-              ON application_settings.id = 1
+            JOIN application_settings ON (TRUE)
             WHERE ci_builds.type = 'Ci::Build'
               AND ci_builds.status = '%s'
               -- The created_at filter has been introduced for performance reasons only
@@ -95,8 +94,7 @@ module GitLab
               ON namespaces.id = projects.namespace_id
             LEFT JOIN namespace_statistics
               ON namespace_statistics.namespace_id = namespaces.id
-            JOIN application_settings
-              ON application_settings.id = 1
+            JOIN application_settings ON (TRUE)
             WHERE ci_builds.type = 'Ci::Build'
               AND ci_builds.status = 'running'
               -- The created_at filter has been introduced for performance reasons only
@@ -175,8 +173,7 @@ module GitLab
                 ON namespaces.id = projects.namespace_id
               LEFT JOIN namespace_statistics
                 ON namespace_statistics.namespace_id = namespaces.id
-              JOIN application_settings
-                ON application_settings.id = 1
+              JOIN application_settings ON (TRUE)
               WHERE ci_builds.type = 'Ci::Build'
                 AND ci_builds.status IN ('running', 'pending')
                 -- The created_at filter has been introduced for performance reasons only

lib/gitlab_exporter/version.rb

 module GitLab
   module Exporter
-    VERSION = "7.0.5".freeze
+    VERSION = "7.0.6".freeze
   end
 end