Blockstore: Migrate ShredIndex type to more efficient data structure #16173

Job	Run time
test_cli (single-pool)	3m 25s
test_cli (token-2022)	3m 22s
check (associated-token-account)	1m 20s
cargo-test-sbf (associated-token-account)	3m 24s
check (feature-proposal)	2m 41s
cargo-test-sbf (feature-proposal)	3m 21s
check (instruction-padding)	1m 0s
check (memo)	1m 7s
check (record)	54s
cargo-test-sbf (instruction-padding)	3m 22s
check (single-pool)	3m 22s
cargo-test-sbf (memo)	3m 21s
check (slashing)	2m 16s
cargo-test-sbf (record)	3m 22s
check (stake-pool)	2m 17s
cargo-test-sbf (single-pool)	3m 21s
check (token-2022)	2m 39s
cargo-test-sbf (slashing)	3m 22s
cargo-test-sbf (stake-pool)	3m 22s
cargo-test-sbf (token-2022)	3m 21s
	54m 39s

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