Event mixing: Do not use arrow functions in groupTable

[saganatt]

Rewrite groupTable() to use the O2 table iterators instead of manually iterating over Apache Arrow chunked columns.
Credits to @mytkom for the idea and most of the implementation.

It gives a 2x speed-up to the creation of a blocked combination policy -- see the results (mean of 5 benchmark runs) in the table below.
This does not affect the running time of creation of a combination generator and generation of combinations.

Table size	Real time after the simplification (ns)	Real time before the simplification (ns)
4	282.39	713.76
8	402.68	1,121.59
16	646.18	1,911.54
32	1,102.81	3,364.43
64	2,090.18	6,332.45
128	3,945.50	12,165.50
256	7,946.86	23,717.70
512	16,024.30	46,894.60
1024	32,856.40	95,093.30
2048	67,987.50	192,691.00
4096	150,429.00	392,947.00
8192	336,427.00	825,430.00
16384	716,285.00	1,674,110.00
32768	1,467,430.00	3,434,070.00
65536	3,011,900.00	6,886,320.00
131072	6,172,810.00	13,968,900.00
262144	12,517,400.00	28,290,700.00
524288	25,900,100.00	57,190,100.00
1048576	58,248,200.00	120,218,000.00
2097152	136,993,000.00	262,650,000.00

FYI @mytkom @chefxxx @MykhailoShamrai

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[alibuild]

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[ktf]

Looks good, thanks. Which tests did you do to validate the results?

[saganatt]

Looks good, thanks. Which tests did you do to validate the results?

I ran event mixing tutorial tasks (file eventMixing.cxx in O2Physics/Tutorials/src) and checked that the console output of these tasks doesn't change with this PR.

I performed the benchmark with the following code that is not merged yet, but I can make a PR for that after my vacations: https://github.com/saganatt/AliceO2/blob/mixing-benchmark-simplify-group-table/Framework/Core/test/benchmark_EventMixingParts.cxx