[Bug] Fix the problem of mem exec, when analytic eval node need to spill to disk with a low mem limit.
And clear_reservations of Analytic node reservation of block manager.
[Running Profile] Add Spilled flag in Running Profile, when Analytic eval node and sort node spill to Disk.
* 1. Add enable spilling in query option, support spill disk in Analytic_Eval_Node, FE can open enable spilling by
set enable_spilling = true;
Now, Sort Node and Analytic_Eval_Node can spill to disk.
2. Delete merge merge_sorter code we do not use now.
3. Replace buffered_tuple_stream by buffered_tuple_stream2 in Analytic_Eval_Node and support spill to disk. Delete the useless code of buffered_block_mgr and buffered_tuple_stream.
4. Add DataStreamRecvr Profile. Move the counter belong to DataStreamRecvr from fragment to DataStreamRecvr Profile to make clear of Running Profile.
* change some hint in code
* replace disable_spill with enable_spill which is better compatible to FE
Help to locate big query when system overload, by checking consumptions of running parts of current all queries or specified one query. Its basic mode of work is as follows: firstly trigger BE to report RuntimeProfiles, and wait a moment. secondly caculate consumptions with RuntimeProfiles reported by BE. The consumptions supported by it are the cost of running ExecNode in query when call it.
