br: remove duplicated release notes from release-8.3.0.md

Signed-off-by: Aolin <[email protected]>

releases/release-8.3.0.md

@@ -307,7 +307,6 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v8.3/quick-start-with-
         - Support checking whether the disk space in TiKV and TiFlash is sufficient before restoring snapshot backups. If the space is insufficient, BR terminates the restore and returns an error [#54316](https://github.com/pingcap/tidb/issues/54316) @[RidRisR](https://github.com/RidRisR)
         - Support checking whether the disk space in TiKV is sufficient before TiKV downloads each SST file. If the space is insufficient, BR terminates the restore and returns an error [#17224](https://github.com/tikv/tikv/issues/17224) @[RidRisR](https://github.com/RidRisR)
         - Support setting Alibaba Cloud access credentials through environment variables [#45551](https://github.com/pingcap/tidb/issues/45551) @[RidRisR](https://github.com/RidRisR)
-        - Optimize the backup feature, improving backup performance and stability during node restarts, cluster scaling-out, and network jitter when backing up large numbers of tables [#52534](https://github.com/pingcap/tidb/issues/52534) @[3pointer](https://github.com/3pointer)
         - Automatically set the environment variable `GOMEMLIMIT` based on the available memory of the BR process to avoid OOM when using BR for backup and restore [#53777](https://github.com/pingcap/tidb/issues/53777) @[Leavrth](https://github.com/Leavrth)
         - Make incremental backups compatible with point-in-time recovery (PITR) [#54474](https://github.com/pingcap/tidb/issues/54474) @[3pointer](https://github.com/3pointer)
         - Support backing up and restoring the `mysql.column_stats_usage` table [#53567](https://github.com/pingcap/tidb/issues/53567) @[hi-rustin](https://github.com/Rustin170506)