Revert the background job to clear unreferenced state groups (that was introduced in v1.126.0rc1), due to a suspected issue that causes increased disk usage. (#18222)

Revert "Add background job to clear unreferenced state groups (#18154)"

This mechanism is suspected of inserting large numbers of rows into
`state_groups_state`,
thus unreasonably increasing disk usage.

See: https://github.com/element-hq/synapse/issues/18217

This reverts commit 5121f9210c989fcc909e78195133876dff3bc9b9 (#18154).

---------

Signed-off-by: Olivier 'reivilibre <oliverw@matrix.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/development/database_schema.md b/docs/development/database_schema.md

index 620d1c16b0..37a06acc12 100644
--- a/docs/development/database_schema.md
+++ b/docs/development/database_schema.md
@@ -162,7 +162,7 @@ by a unique name, the current status (stored in JSON), and some dependency infor
 * Whether the update requires a previous update to be complete.
 * A rough ordering for which to complete updates.
 
-A new background update needs to be added to the `background_updates` table:
+A new background updates needs to be added to the `background_updates` table:
 
 ```sql
 INSERT INTO background_updates (ordering, update_name, depends_on, progress_json) VALUES