case of test_string_concat_extremely_long_string will exceed our test limit. Move it to p2 so that it will be tested only in SelectDB test environment.
Because we need to keep consistent with MySQL & avoid overflow. the q67 must keep its behavior like now. When we fully apply nereids & decimalV3 then, it will be fixed automatically.
In the parallel test, although all query stats were cleaned, the cases run in parallel will affect this. So we need to use a unique table for query_stats_test
test_query_sys_tables didn't deal with some unstable situations. fixed it.
temporarily disable unstable case analyze_test case for p0.
