Fix docs documenting invalid @every for OLDER_THAN cron settings (#24695)

Looks like a copy-paste leftover

- Fixes #20868

Co-authored-by: Giteabot <[email protected]>

Author: yardenshoham

docs/content/doc/administration/config-cheat-sheet.en-us.md

@@ -1018,7 +1018,7 @@ Default templates for project boards:
 - `RUN_AT_START`: **false**: Run tasks at start up time (if ENABLED).
 - `NOTICE_ON_SUCCESS`: **false**: Set to true to switch on success notices.
 - `SCHEDULE`: **@every 168h**: Cron syntax to set how often to check.
-- `OLDER_THAN`: **@every 8760h**: any action older than this expression will be deleted from database, suggest using `8760h` (1 year) because that's the max length of heatmap.
+- `OLDER_THAN`: **8760h**: any action older than this expression will be deleted from database, suggest using `8760h` (1 year) because that's the max length of heatmap.
 
 #### Cron -  Check for new Gitea versions (`cron.update_checker`)
 
@@ -1034,7 +1034,7 @@ Default templates for project boards:
 - `RUN_AT_START`: **false**: Run tasks at start up time (if ENABLED).
 - `NO_SUCCESS_NOTICE`: **false**: Set to true to switch off success notices.
 - `SCHEDULE`: **@every 168h**: Cron syntax to set how often to check.
-- `OLDER_THAN`: **@every 8760h**: any system notice older than this expression will be deleted from database.
+- `OLDER_THAN`: **8760h**: any system notice older than this expression will be deleted from database.
 
 #### Cron -  Garbage collect LFS pointers in repositories (`cron.gc_lfs`)