enh:  prealloc handle

fix: client module memory leak problem

others: remove obsolete 2.0 code

test: restore some 2.0 case

fix(query): add exec node for lastrow query.

test: restore some 2.0 case

fix(query): fix memory leak.

feat(query): add stddev function scalar version 

feat(query): add sum/count/max/min function scalar version

test:add test case for tmq

fix(query): handle the grouped fill.

refactor(stream): destroy stream task

test: restore some 2.0 case

TD-17344

fix: some problems of planner

fix:error in json tag