Small optimizations on iggen buffer handling #4838

Job	Run time
clang-tidy	3m 32s
read-build-matrix	8s
build-and-test (dpcpp, ad494e9d, false, 22.04, intel, Debug)	4m 13s
build-and-test (dpcpp, ad494e9d, false, 22.04, intel, Release)	3m 39s
build-and-test (dpcpp, latest, true, 24.04, intel, Debug)	4m 3s
build-and-test (dpcpp, latest, true, 24.04, intel, Release)	4m 20s
build-and-test (acpp, v24.06.0, false, 22.04, nvidia, Debug)	2m 18s
build-and-test (acpp, v24.06.0, false, 22.04, nvidia, Release)	5m 19s
build-and-test (acpp, latest, true, 24.04, nvidia, Debug)	4m 49s
build-and-test (acpp, latest, true, 24.04, nvidia, Release)	6m 5s
build-and-test (simsycl, HEAD, true, 24.04, intel, Release)	2m 8s
build-and-test (simsycl, HEAD, true, 24.04, intel, Debug)	12m 15s
report	0s
tag-latest-containers	0s
	52m 49s

Provide feedback