metrics: remove optimistic_slot_elapsed #9826

Job	Run time
cargo-test-sbf (token/program)	8m 34s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	16m 5s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	9m 13s
check	2m 53s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	17m 11s
cargo-test-sbf (token-upgrade/program)	8m 46s
test (single-pool/cli, single-pool/program)	17m 6s
cargo-test-sbf (feature-proposal/program)	8m 26s
test (token-upgrade/cli, token-upgrade/program)	15m 49s
cargo-test-sbf (governance/addin-mock/program, governance/program)	12m 50s
cargo-test-sbf (memo/program)	8m 59s
cargo-test-sbf (name-service/program)	8m 15s
cargo-test-sbf (stake-pool/program)	11m 16s
cargo-test-sbf (single-pool/program)	9m 2s
	2h 34m 25s

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