tools/create-image.sh: update default Debian release to trixie #18433

Job	Run time
aux	4m 37s
build	5m 15s
race_dashboard	2m 54s
gvisor	4m 5s
arch (presubmit_arch_darwin)	3m 42s
old	7m 10s
arch (presubmit_arch_windows)	3m 31s
arch (presubmit_arch_netbsd)	3m 53s
race	9m 19s
arch (presubmit_arch_freebsd)	6m 33s
arch (presubmit_arch_openbsd)	3m 49s
dashboard	2m 41s
arch (presubmit_arch_linux)	10m 55s
arch (presubmit_arch_executor)	3m 1s
	1h 11m 25s

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