Evaluate Case When Expr in Fe when possible

[wangbo]

In the query case partition column compare with a case when Expr, evaluate Case when Expr in Fe can void unnecessary partition scan.

See a example as below

SQL

select event_day,sum(pv) from table2 where 
event_day= case when date_format(now(),'%H%i') = 0 then 1 else 2 end group by event_day

BEFORE

 0:OlapScanNode |
| TABLE: table2 |
| PREAGGREGATION: ON |
| PREDICATES: `event_day` = CASE WHEN FALSE THEN 1 ELSE 2 END |
| partitions=1/3 |
| rollup: table2 |
| buckets=10/10 |
| cardinality=14 |
| avgRowSize=723.5714 |
| numNodes=1 |
| tuple ids: 0 

AFTER

 0:OlapScanNode |
| TABLE: table2 |
| PREAGGREGATION: ON |
| PREDICATES: `event_day` = 2.0 |
| partitions=1/3 |
| rollup: table2 |
| buckets=10/10 |
| cardinality=14 |
| avgRowSize=723.5714 |
| numNodes=1 |
| tuple ids: 0