Optimize AccountIndexIterator to reuse last loaded bin-map item range #18983

Job	Run time
check (associated-token-account)	1m 27s
test_cli (single-pool)	17m 42s
check (feature-proposal)	1m 54s
test_cli (token-2022)	16m 34s
check (instruction-padding)	1m 12s
check (memo)	1m 10s
check (record)	53s
cargo-test-sbf (associated-token-account)	8m 20s
check (single-pool)	4m 46s
cargo-test-sbf (feature-proposal)	6m 59s
check (slashing)	1m 36s
cargo-test-sbf (instruction-padding)	6m 19s
check (stake-pool)	2m 32s
cargo-test-sbf (memo)	5m 49s
check (token-2022)	2m 37s
cargo-test-sbf (record)	6m 54s
cargo-test-sbf (single-pool)	8m 3s
cargo-test-sbf (slashing)	14m 11s
cargo-test-sbf (stake-pool)	10m 30s
cargo-test-sbf (token-2022)	7m 33s
	2h 7m 1s

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