Consolidates duplicate promote error in Geo troubleshooting docs

There are two duplicate sections in the troubleshooting docs for
the same error when promoting a paused secondary, this converges
the two in a single section and a single solution.

doc/administration/geo/disaster_recovery/index.md

@@ -100,7 +100,7 @@ Note the following when promoting a secondary:
 
 - If replication was paused on the secondary node, for example as a part of upgrading,
   while you were running a version of GitLab lower than 13.4, you _must_
-  [enable the node via the database](../replication/troubleshooting.md#while-promoting-the-secondary-i-got-an-error-activerecordrecordinvalid)
+  [enable the node via the database](../replication/troubleshooting.md#message-activerecordrecordinvalid-validation-failed-enabled-geo-primary-node-cannot-be-disabled)
   before proceeding.
 - A new **secondary** should not be added at this time. If you want to add a new
   **secondary**, do this after you have completed the entire process of promoting

doc/administration/geo/replication/troubleshooting.md

@@ -614,46 +614,17 @@ or `gitlab-ctl promote-to-primary-node`, either:
 
 ### Message: ActiveRecord::RecordInvalid: Validation failed: Enabled Geo primary node cannot be disabled
 
-This error may occur if you have paused replication from the original primary node before attempting to promote this node.
-To double check this, you can do the following:
-
-- Get the current secondary node's ID using:
-
-  ```shell
-  sudo gitlab-rails runner 'puts GeoNode.current_node.id'
-  ```
-
-- Double check that the node is active through the database by running the following
-  on the secondary node, replacing `ID_FROM_ABOVE`:
-
-  ```shell
-  sudo gitlab-rails dbconsole
-
-  SELECT enabled FROM geo_nodes WHERE id = ID_FROM_ABOVE;
-  ```
-
-- If the above returned `f` it means that the replication was paused.
-  You can re-enable it through an `UPDATE` statement in the database:
-
-  ```shell
-  sudo gitlab-rails dbconsole
-
-  UPDATE geo_nodes SET enabled = 't' WHERE id = ID_FROM_ABOVE;
-  ```
-
-### While Promoting the secondary, I got an error `ActiveRecord::RecordInvalid`
-
 If you disabled a secondary node, either with the [replication pause task](../index.md#pausing-and-resuming-replication)
 (13.2) or via the UI (13.1 and earlier), you must first re-enable the
 node before you can continue. This is fixed in 13.4.
 
-From `gitlab-psql`, execute the following, replacing  `<your secondary url>`
-with the URL for your secondary server starting with `http` or `https` and ending with a `/`.
+Execute the following, replacing  `<your secondary url>` with the URL for your secondary
+server, using `http` or `https` and ending with a `/`.
 
 ```shell
-SECONDARY_URL="https://<secondary url>/"
-DATABASE_NAME="gitlabhq_production"
-sudo gitlab-psql -d "$DATABASE_NAME" -c "UPDATE geo_nodes SET enabled = true WHERE url = '$SECONDARY_URL';"
+sudo gitlab-rails dbconsole
+
+UPDATE geo_nodes SET enabled = true WHERE url = 'https://<secondary url>/';"
 ```
 
 This should update 1 row.