v2.1: make new_from_bank to be only for tests (backport of #3455) #12728

Job	Run time
check	4m 10s
cargo-test-sbf (token/program)	9m 1s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	18m 38s
test (single-pool/cli, single-pool/program)	18m 29s
test (token-upgrade/cli, token-upgrade/program)	17m 46s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	15m 17s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	11m 50s
cargo-test-sbf (token-upgrade/program)	9m 46s
cargo-test-sbf (feature-proposal/program)	8m 15s
cargo-test-sbf (governance/addin-mock/program, governance/program)	13m 32s
cargo-test-sbf (memo/program)	9m 0s
cargo-test-sbf (name-service/program)	8m 23s
cargo-test-sbf (stake-pool/program)	13m 19s
cargo-test-sbf (single-pool/program)	10m 21s
	2h 47m 47s

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