1. add a post processor: runtime filter pruner
Doris generates RFs (runtime filter) on Join node to reduce the probe table at scan stage. But some RFs have no effect, because its selectivity is 100%. This pr will remove them.
A RF is effective if
a. the build column value range covers part of that of probe column, OR
b. the build column ndv is less than that of probe column, OR
c. the build column's ColumnStats.selectivity < 1, OR
d. the build column is reduced by another RF, which satisfies above criterions.
2. explain graph
a. add RF info in Join and Scan node
b. add predicate count in Scan node
3. Rename session variable
rename `enable_remove_no_conjuncts_runtime_filter_policy` to `enable_runtime_filter_prune`
4. fix min/max column stats derive bug
`select max(A) as X from T group by B`
X.min is A.min, not A.max
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