v2.0: banking_stage: do not insert legacy vote ixs, refactor & unstaked (backport of #2888) #10362

Job	Run time
cargo-test-sbf (token/program)	7m 38s
check	4m 44s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	14m 58s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	9m 54s
cargo-test-sbf (token-upgrade/program)	8m 50s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	18m 56s
cargo-test-sbf (feature-proposal/program)	7m 39s
test (single-pool/cli, single-pool/program)	18m 25s
cargo-test-sbf (governance/addin-mock/program, governance/program)	11m 33s
test (token-upgrade/cli, token-upgrade/program)	13m 11s
cargo-test-sbf (memo/program)	7m 5s
cargo-test-sbf (name-service/program)	8m 39s
cargo-test-sbf (stake-pool/program)	14m 6s
cargo-test-sbf (single-pool/program)	8m 43s
	2h 34m 21s

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