ddl: stabilize test TestAddPrimaryKeyRollback1 (#21492)
ddl: stabilize test TestAddPrimaryKeyRollback1 (#21492)

Signed-off-by: wjhuang2016 <8a483867dd4989e49147ceee396e2d7e52a5faa7@gmail.com>
kyle-wang/tidb,kyle-wang/tidb,kyle-wang/tidb,ngaut/tidb,kyle-wang/tidb,c4pt0r/tidb,coocood/tidb,ngaut/tidb,c4pt0r/tidb,c4pt0r/tidb,pingcap/tidb,kyle-wang/tidb,ngaut/tidb,pingcap/tidb,coocood/tidb,pingcap/tidb,c4pt0r/tidb,kyle-wang/tidb,ngaut/tidb,c4pt0r/tidb,c4pt0r/tidb,pingcap/tidb,pingcap/tidb,ngaut/tidb,pingcap/tidb,ngaut/tidb