Optimize `merge` algorithm for largest data sizes #146

Job	Run time
clang-format	12s
HOST,bknd=omp,cmplr=clang++,macos-latest,std=c++17,cfg=release	4m 28s
HOST,bknd=tbb,cmplr=icx-cl,windows-latest,std=c++17,cfg=release	18m 50s
HOST,bknd=tbb,cmplr=cl,windows-latest,std=c++17,cfg=release	15m 40s
CPU,bknd=dpcpp,cmplr=icx,windows-latest,std=c++17,cfg=release	11m 31s
CPU,bknd=dpcpp,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	15m 26s
FPGA_EMU,bknd=dpcpp,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	23m 52s
HOST,bknd=tbb,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	11m 31s
HOST,bknd=omp,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	9m 41s
HOST,bknd=omp,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	5m 59s
HOST,bknd=tbb,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	8m 49s
HOST,bknd=tbb,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	8m 44s
HOST,bknd=tbb,cmplr=clang++,ubuntu-latest,std=с++17,cfg=release	11m 10s
HOST,bknd=omp,cmplr=clang++,ubuntu-latest,std=с++17,cfg=release	8m 27s
HOST,bknd=tbb,cmplr=clang++,ubuntu-latest,std=с++17,cfg=release	10m 52s
HOST,bknd=tbb,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	11m 28s
HOST,bknd=serial,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	4m 53s
CPU,bknd=dpcpp,cmplr=icpx,ubuntu-latest,std=с++20,cfg=release	27m 5s
HOST,bknd=tbb,cmplr=icpx,ubuntu-latest,std=с++20,cfg=release	17m 46s
HOST,bknd=omp,cmplr=icpx,ubuntu-latest,std=с++20,cfg=release	18m 9s
	4h 4m 33s

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