cleanup feature code after activation #5870

Job	Run time
check	0s
cargo-test-sbf (token/program)	9m 54s
test	0s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	15m 56s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	9m 14s
cargo-test-sbf (token-upgrade/program)	8m 21s
cargo-test-sbf (feature-proposal/program)	9m 35s
cargo-test-sbf (governance/addin-mock/program, governance/program)	12m 24s
cargo-test-sbf (memo/program)	8m 37s
cargo-test-sbf (name-service/program)	10m 11s
cargo-test-sbf (stake-pool/program)	11m 55s
cargo-test-sbf (single-pool/program)	9m 42s
	1h 45m 49s

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