test: fix data race of Kill (#27864)
test: fix data race of Kill (#27864)

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