starknet_os_flow_tests: extract test contract constructor calldata helpers

[AvivYossef-starkware]

Summary

• Adds two helpers near the top of crates/starknet_os_flow_tests/src/tests.rs:
  • test_contract_constructor_calldata(my_storage_var_addend_1, my_storage_var_addend_2) — named constructor builder. Doc comment notes that TestContract::constructor writes arg1 + arg2 to my_storage_var.
  • default_test_contract_constructor_calldata() — calls the above with (Felt::ZERO, Felt::ZERO).
• Replaces 19 occurrences of calldata![Felt::ZERO, Felt::ZERO] (paired with TestContract(...) everywhere) with default_test_contract_constructor_calldata().
• Replaces 5 occurrences of calldata![Felt::ONE, Felt::TWO] with test_contract_constructor_calldata(Felt::ONE, Felt::TWO).

Addresses the review comment on #14042 (reviewable thread) — calldata![Felt::ZERO, Felt::ZERO] was opaque at the call site; the named helpers make the role of the felts (constructor args summed into my_storage_var) obvious without digging into the Cairo source.

Stacked on top of #14042 — only this one commit is new.

Test plan

• cargo check -p starknet_os_flow_tests --tests ✅
• scripts/rust_fmt.sh ✅
• Behavior unchanged — purely mechanical rename of literals + two new helper definitions. No new logic.

[reviewable-StarkWare]

This change is 

[cursor]

PR Summary

Low Risk
Low risk: test-only refactor that replaces repeated constructor calldata literals with small helper functions, with no behavioral changes intended.

Overview
Introduces two small helpers in starknet_os_flow_tests to build TestContract constructor calldata (including a default that keeps my_storage_var at zero), documenting the constructor’s side effect.

Replaces many inline calldata![Felt::ZERO, Felt::ZERO] / calldata![Felt::ONE, Felt::TWO] occurrences across tests with these helpers to make constructor intent explicit and reduce duplication.

^{Reviewed by Cursor Bugbot for commit fbe3ce8. Bugbot is set up for automated code reviews on this repo. Configure here.}

[Yoni-Starkware]

@Yoni-Starkware reviewed 1 file and all commit messages, and made 2 comments.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on AvivYossef-starkware).

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crates/starknet_os_flow_tests/src/tests.rs line 285 at r1 (raw file):

    let (mut test_builder, [test_contract_address]) = TestBuilder::create_standard_with_config(
        [(test_contract, test_contract_constructor_calldata(Felt::ONE, Felt::TWO))],

Since it's either 0,0 or 1,2, I'd add another function for the 1,2 case. nontrivial_constructor_calldata

Code quote:

       [(test_contract, test_contract_constructor_calldata(Felt::ONE, Felt::TWO))],