Small optimizations on iggen buffer handling #4764

Job	Run time
read-build-matrix	7s
clang-tidy	2m 49s
build-and-test (dpcpp, ad494e9d, false, 22.04, intel, Debug)	3m 38s
build-and-test (dpcpp, ad494e9d, false, 22.04, intel, Release)	3m 6s
build-and-test (dpcpp, latest, true, 24.04, intel, Debug)	4m 27s
build-and-test (dpcpp, latest, true, 24.04, intel, Release)	3m 46s
build-and-test (acpp, v24.06.0, false, 22.04, nvidia, Debug)	4m 3s
build-and-test (acpp, v24.06.0, false, 22.04, nvidia, Release)	4m 55s
build-and-test (acpp, latest, true, 24.04, nvidia, Debug)	4m 31s
build-and-test (acpp, latest, true, 24.04, nvidia, Release)	13m 12s
build-and-test (simsycl, HEAD, true, 24.04, intel, Release)	2m 10s
build-and-test (simsycl, HEAD, true, 24.04, intel, Debug)	8m 49s
report	21s
tag-latest-containers	0s
	55m 54s

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