add --cleanup flag (default true) #2590

Job	Run time
Build melange and add to artifact cache	37s
Build packages (bubblewrap, hello-wolfi)	1m 15s
Build packages (bubblewrap, glibc)	11m 31s
Build packages (bubblewrap, tini)	4m 3s
Build packages (bubblewrap, lzo)	1m 14s
Build packages (bubblewrap, bubblewrap)	1m 6s
Build packages (bubblewrap, gitsign)	2m 32s
Build packages (bubblewrap, guac)	3m 29s
Build packages (bubblewrap, mdbook)	3m 44s
Build packages (bubblewrap, s3cmd)	1m 19s
Build packages (bubblewrap, perl-yaml-syck)	1m 6s
Build packages (bubblewrap, ncurses)	2m 15s
Build packages (qemu, hello-wolfi)	1m 45s
Build packages (qemu, glibc)	12m 35s
Build packages (qemu, tini)	2m 13s
Build packages (qemu, lzo)	2m 6s
Build packages (qemu, bubblewrap)	1m 34s
Build packages (qemu, gitsign)	3m 13s
Build packages (qemu, guac)	4m 47s
Build packages (qemu, mdbook)	4m 34s
Build packages (qemu, s3cmd)	1m 58s
Build packages (qemu, perl-yaml-syck)	1m 59s
Build packages (qemu, ncurses)	2m 46s
	1h 13m 41s

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