*: update unstable unit test case list (#33147)

ref #32303

unstable.txt

@@ -1,5 +1,34 @@
 ddl TestModifyColumn
+ddl TestModifyColumnTypeWhenInterception
 util/cpuprofile TestGetCPUProfile
 executor TestDefaultValForAnalyze
 executor TestPBMemoryLeak
 executor TestInvalidReadCacheTable
+executor TestCancelMppTasks
+executor testSuite.TestTimestampDefaultValueTimeZone
+executor TestIndexJoin31494
+executor TestInvalidReadCacheTable
+executor TestPartitionTable
+executor TestRangePartitionBoundariesLtM
+server TestTopSQLCPUProfile
+server TestErrorNoRollback
+server TestUint64
+planner/core TestIssue27544
+planner/core TestIssue20139
+planner/core TestAggPushToCopForCachedTable
+planner/core TestIssue23887
+planner/core TestOrderedResultModeOnJoin
+planner/core TestCompareSubquery
+planner/core TestEstimation
+planner/core TestPlanStringer
+planner/core TestMultiColInExpression
+planner/core TestIssue16407
+planner/core TestPrepareCacheNow
+planner/core TestDAGPlanBuilderSplitAvg
+planner/core TestIndexMerge
+planner/core TestUnmatchedTableInHint
+planner/core TestPartitionWithVariedDataSources
+planner/core TestCopPaging
+planner/core TestPlanCachePointGetAndTableDual
+planner/core TestSimplifyOuterJoinWithCast 
+executor/seqtest TestShow