calculate ancient slot boundary correctly for hash calc (#2444) #8544

Job	Run time
check	3m 0s
cargo-test-sbf (token/program)	8m 19s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	16m 36s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	19m 37s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	16m 53s
test (single-pool/cli, single-pool/program)	24m 52s
test (token-upgrade/cli, token-upgrade/program)	23m 3s
cargo-test-sbf (token-upgrade/program)	8m 26s
cargo-test-sbf (feature-proposal/program)	10m 32s
cargo-test-sbf (governance/addin-mock/program, governance/program)	11m 41s
cargo-test-sbf (memo/program)	19m 43s
cargo-test-sbf (name-service/program)	10m 8s
cargo-test-sbf (stake-pool/program)	12m 13s
cargo-test-sbf (single-pool/program)	11m 11s
	3h 16m 14s

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