iwyu.yml: added `diskarzhan` job #522

Job	Run time
iwyu (macos-26, libc++, -Xiwyu --mapping_file=$(realpath ./macos.imp))	4m 22s
iwyu (ubuntu-22.04, fedora:rawhide, libc++)	7m 21s
diskarzhan	16s
clang-include-cleaner (libstdc++)	7m 57s
iwyu (ubuntu-22.04, fedora:rawhide, libstdc++)	6m 18s
clang-include-cleaner (libc++)	10m 38s
	36m 52s

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