Parametrize the CURRENT_STORAGE_VERSION migration test

[Jaydbrown]

Add a test that simulates a v0 (pre-consolidation) stream and asserts the first save() migrates it and removes legacy keys, for every version bump.

[ZacLou]

I'd like to work on this issue. I have relevant experience with this tech stack and can deliver a clean, well-tested PR. I can submit within 1-2 days.

[ZacLou]

I'd like to work on this — opened a PR at #520.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@ZacLou's PR #520 was approved and merged by @Jaydbrown.

🏆 @ZacLou: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (643 total points). Track your full progress on GrantFox.

👏 Great work, @ZacLou! Keep contributing to conduit-protocol.