Refactor - Makes loader-v4 the default #12679

Job	Run time
cargo-test-sbf (token/program)	10m 8s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	20m 4s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	15m 9s
check	2m 56s
test (single-pool/cli, single-pool/program)	19m 44s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	11m 6s
test (token-upgrade/cli, token-upgrade/program)	19m 1s
cargo-test-sbf (token-upgrade/program)	9m 9s
cargo-test-sbf (feature-proposal/program)	9m 6s
cargo-test-sbf (governance/addin-mock/program, governance/program)	12m 36s
cargo-test-sbf (memo/program)	7m 55s
cargo-test-sbf (name-service/program)	8m 44s
cargo-test-sbf (stake-pool/program)	11m 46s
cargo-test-sbf (single-pool/program)	10m 52s
	2h 48m 16s

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