indexer-alt: simplify duration command-line parsing #79470

Job	Run time
license-check	1m 4s
diff	8s
test (ubuntu-ghcloud)	36m 52s
test-extra (ubuntu-ghcloud)	24m 45s
windows-build (windows-ghcloud)	9m 10s
clippy	3m 23s
move-test	0s
rustfmt	22s
simtest	15m 49s
test-extra	0s
test	0s
cargo-deny (advisories)	32s
cargo-deny (bans, licenses, sources)	39s
cutting a new execution layer	1m 22s
	1h 34m 6s

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