[alt_bn128 syscalls] Remove extra `Vec` allocation when deserializing curve point types #12688

Job	Run time
check	4m 15s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	19m 56s
cargo-test-sbf (token/program)	8m 27s
test (single-pool/cli, single-pool/program)	20m 20s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	14m 50s
test (token-upgrade/cli, token-upgrade/program)	18m 33s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	11m 8s
cargo-test-sbf (token-upgrade/program)	8m 16s
cargo-test-sbf (feature-proposal/program)	8m 3s
cargo-test-sbf (governance/addin-mock/program, governance/program)	13m 46s
cargo-test-sbf (memo/program)	7m 54s
cargo-test-sbf (name-service/program)	8m 18s
cargo-test-sbf (stake-pool/program)	13m 7s
cargo-test-sbf (single-pool/program)	9m 59s
	2h 46m 52s

Provide feedback