Optimize `merge` algorithm for largest data sizes #147

Job	Run time
clang-format	13s
CPU,bknd=dpcpp,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	11m 56s
HOST,bknd=omp,cmplr=clang++,macos-latest,std=c++17,cfg=release	5m 13s
FPGA_EMU,bknd=dpcpp,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	11m 57s
HOST,bknd=tbb,cmplr=icx-cl,windows-latest,std=c++17,cfg=release	11m 24s
HOST,bknd=tbb,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	11m 40s
HOST,bknd=omp,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	10m 5s
HOST,bknd=tbb,cmplr=cl,windows-latest,std=c++17,cfg=release	11m 44s
HOST,bknd=omp,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	5m 58s
CPU,bknd=dpcpp,cmplr=icx,windows-latest,std=c++17,cfg=release	11m 24s
HOST,bknd=tbb,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	8m 44s
HOST,bknd=tbb,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	8m 59s
HOST,bknd=tbb,cmplr=clang++,ubuntu-latest,std=с++17,cfg=release	10m 55s
HOST,bknd=omp,cmplr=clang++,ubuntu-latest,std=с++17,cfg=release	8m 45s
HOST,bknd=tbb,cmplr=clang++,ubuntu-latest,std=с++17,cfg=release	11m 2s
HOST,bknd=tbb,cmplr=icpx,ubuntu-latest,std=с++17,cfg=release	11m 39s
HOST,bknd=serial,cmplr=g++,ubuntu-latest,std=с++17,cfg=release	4m 56s
CPU,bknd=dpcpp,cmplr=icpx,ubuntu-latest,std=с++20,cfg=release	11m 56s
HOST,bknd=tbb,cmplr=icpx,ubuntu-latest,std=с++20,cfg=release	11m 59s
HOST,bknd=omp,cmplr=icpx,ubuntu-latest,std=с++20,cfg=release	11m 57s
	3h 12m 26s

Provide feedback