Fix stage level metrics output csv file

[nartal1]

This fixes #1250.
This bug is because of grouping the metrics only on accumId. This PR fixes the bug by grouping it both on accumId and stageId such that the result is metrics per stage.
Changed the unit test such that the same accumId is updated in 2 stages and the output will show it in 2 different rows.

Also tested it on custom eventlog where the accumulator updates the value in 2 stages.

Before this PR:

appIndex,stageId,accumulatorId,name,min,median,max,total
1,"0",0,"My Accumulator",1,2,4,300
1,"0",1,"internal.metrics.executorDeserializeTime",626,629,631,40238

With this PR:

appIndex,stageId,accumulatorId,name,min,median,max,total
1,0,0,"My Accumulator",1,2,2,100
1,0,1,"internal.metrics.executorDeserializeTime",626,629,631,40238
1,1,0,"My Accumulator",2,4,4,200

[amahussein]

rapids-tools-pr-1251.patch
Thanks @nartal1 for working on that quick fix
This is a patch to restore the column order.
Since it is stage level report, then it is expected to see the stages coming in order. I also, fixed the type of stageId to be integer because converting it to string turns to be unnecessary overhead from the memory consumption point of view.

The output now looks like this:

appIndex,stageId,accumulatorId,name,min,median,max,total
1,0,0,"My Accumulator",1,2,2,100
1,0,1,"internal.metrics.executorDeserializeTime",626,629,631,40238
1,1,0,"My Accumulator",2,4,4,200

[nartal1]

rapids-tools-pr-1251.patch Thanks @nartal1 for working on that quick fix This is a patch to restore the column order. Since it is stage level report, then it is expected to see the stages coming in order. I also, fixed the type of stageId to be integer because converting it to string turns to be unnecessary overhead from the memory consumption point of view.

The output now looks like this:

appIndex,stageId,accumulatorId,name,min,median,max,total
1,0,0,"My Accumulator",1,2,2,100
1,0,1,"internal.metrics.executorDeserializeTime",626,629,631,40238
1,1,0,"My Accumulator",2,4,4,200

Thanks @amahussein! The output looks cleaner now. Have applied the patch in this PR.

[parthosa]

Thanks @nartal1 for this fix.

[amahussein]

Thanks @nartal1 for the fix.