planner/core: migrate test-infra to testify for planbuilder_test.go (#32445)
planner/core: migrate test-infra to testify for planbuilder_test.go (#32445)

close pingcap/tidb#28392
kyle-wang/tidb,c4pt0r/tidb,pingcap/tidb,pingcap/tidb,kyle-wang/tidb,ngaut/tidb,pingcap/tidb,kyle-wang/tidb,pingcap/tidb,c4pt0r/tidb,ngaut/tidb,c4pt0r/tidb,c4pt0r/tidb,c4pt0r/tidb,ngaut/tidb,pingcap/tidb,ngaut/tidb,kyle-wang/tidb,kyle-wang/tidb,ngaut/tidb,c4pt0r/tidb,pingcap/tidb,ngaut/tidb,kyle-wang/tidb