Update deprecation notes for Tenant Scale

data/deprecations/15-9-database-single-database-connection-conf.yml

 - title: "Single database connection is deprecated"
   announcement_milestone: "15.9"
-  removal_milestone: "17.0"
+  end_of_support_milestone: "17.0"
+  removal_milestone: "18.0"
   breaking_change: true
   reporter: tkuah
   stage: Enablement

data/deprecations/16-1-non-decomposed-mode-deprecation.yml

@@ -9,9 +9,7 @@
     From GitLab 18.0, we will require a [separate database for CI features](https://gitlab.com/groups/gitlab-org/-/epics/7509).
     We recommend running both databases on the same Postgres instance(s) due to ease of management for most deployments.
 
-    We are providing this as an informational advance notice but we do not recommend taking action yet.
-    We will have another update communicated (as well as the deprecation note) when we recommend admins to start the migration process.
-
     This change provides additional scalability for the largest of GitLab instances, like GitLab.com.
     This change applies to all installation methods: Omnibus GitLab, GitLab Helm chart, GitLab Operator, GitLab Docker images, and installation from source.
     Before upgrading to GitLab 18.0, please ensure you have [migrated](https://docs.gitlab.com/ee/administration/postgresql/multiple_databases.html) to two databases.
+  documentation_url: https://docs.gitlab.com/ee/administration/postgresql/multiple_databases.html

doc/update/deprecations.md

@@ -300,9 +300,6 @@ This change is a breaking change. You should [create a runner in the UI](https:/
 From GitLab 18.0, we will require a [separate database for CI features](https://gitlab.com/groups/gitlab-org/-/epics/7509).
 We recommend running both databases on the same Postgres instance(s) due to ease of management for most deployments.
 
-We are providing this as an informational advance notice but we do not recommend taking action yet.
-We will have another update communicated (as well as the deprecation note) when we recommend admins to start the migration process.
-
 This change provides additional scalability for the largest of GitLab instances, like GitLab.com.
 This change applies to all installation methods: Omnibus GitLab, GitLab Helm chart, GitLab Operator, GitLab Docker images, and installation from source.
 Before upgrading to GitLab 18.0, please ensure you have [migrated](https://docs.gitlab.com/ee/administration/postgresql/multiple_databases.html) to two databases.
@@ -337,6 +334,28 @@ For updates and details about this deprecation, follow [this epic](https://gitla
 
 <div class="deprecation breaking-change" data-milestone="18.0">
 
+### Single database connection is deprecated
+
+<div class="deprecation-notes">
+- Announced in GitLab <span class="milestone">15.9</span>
+- End of Support in GitLab <span class="milestone">17.0</span>
+- Removal in GitLab <span class="milestone">18.0</span> ([breaking change](https://docs.gitlab.com/ee/update/terminology.html#breaking-change))
+- To discuss this change or learn more, see the [deprecation issue](https://gitlab.com/gitlab-org/gitlab/-/issues/387898).
+</div>
+
+Previously, [GitLab's database](https://docs.gitlab.com/omnibus/settings/database.html)
+configuration had a single `main:` section. This is being deprecated. The new
+configuration has both a `main:` and a `ci:` section.
+
+This deprecation affects users compiling GitLab from source, who will need
+to [add the `ci:` section](https://docs.gitlab.com/ee/install/installation.html#configure-gitlab-db-settings).
+Omnibus, the Helm chart, and Operator will handle this configuration
+automatically from GitLab 16.0 onwards.
+
+</div>
+
+<div class="deprecation breaking-change" data-milestone="18.0">
+
 ### Slack notifications integration
 
 <div class="deprecation-notes">
@@ -1825,27 +1844,6 @@ In [Support additional filters for scan result policies](https://gitlab.com/grou
 
 <div class="deprecation breaking-change" data-milestone="17.0">
 
-### Single database connection is deprecated
-
-<div class="deprecation-notes">
-- Announced in GitLab <span class="milestone">15.9</span>
-- Removal in GitLab <span class="milestone">17.0</span> ([breaking change](https://docs.gitlab.com/ee/update/terminology.html#breaking-change))
-- To discuss this change or learn more, see the [deprecation issue](https://gitlab.com/gitlab-org/gitlab/-/issues/387898).
-</div>
-
-Previously, [GitLab's database](https://docs.gitlab.com/omnibus/settings/database.html)
-configuration had a single `main:` section. This is being deprecated. The new
-configuration has both a `main:` and a `ci:` section.
-
-This deprecation affects users compiling GitLab from source, who will need
-to [add the `ci:` section](https://docs.gitlab.com/ee/install/installation.html#configure-gitlab-db-settings).
-Omnibus, the Helm chart, and Operator will handle this configuration
-automatically from GitLab 16.0 onwards.
-
-</div>
-
-<div class="deprecation breaking-change" data-milestone="17.0">
-
 ### Support for self-hosted Sentry versions 21.4.1 and earlier
 
 <div class="deprecation-notes">