Use 72 WU instead of 73 WU for signature weight #20952

Job	Run time
fuzz	1h 4m 18s
check_release	2m 55s
benchmark	17m 33s
build (self-hosted, stable)	1h 55m 41s
build (self-hosted, 1.75.0)	1h 27m 7s
build (windows-latest, stable)	2h 23m 49s
linting	2m 47s
build (self-hosted, beta)	1h 44m 42s
build-tx-sync (ubuntu-latest, stable)	4m 50s
build (macos-latest, 1.75.0)	2h 18m 51s
build (macos-latest, stable)	2h 5m 8s
build-tx-sync (ubuntu-latest, 1.75.0)	5m 36s
ext-test	8m 9s
build-tx-sync (macos-latest, 1.75.0)	7m 51s
rustfmt	15s
build-tx-sync (macos-latest, beta)	7m 24s
build-tx-sync (macos-latest, stable)	6m 58s
check_docs	4m 31s
build-tx-sync (ubuntu-latest, beta)	5m 1s
coverage	34m 54s
	14h 48m 20s

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