metrics: add metrics dashboards for sync-load (#30812)
metrics: add metrics dashboards for sync-load (#30812)

 
ngaut/tidb,pingcap/tidb,ngaut/tidb,c4pt0r/tidb,kyle-wang/tidb,c4pt0r/tidb,pingcap/tidb,kyle-wang/tidb,ngaut/tidb,c4pt0r/tidb,pingcap/tidb,pingcap/tidb,pingcap/tidb,c4pt0r/tidb,ngaut/tidb,kyle-wang/tidb,ngaut/tidb,pingcap/tidb,kyle-wang/tidb,c4pt0r/tidb,kyle-wang/tidb,c4pt0r/tidb,kyle-wang/tidb,ngaut/tidb