fix(cli): filter benign time-relative AppSync ApiKey /Expires drift

[sarayev]

Summary

Adds a false-positive filter for AppSync ApiKey /Expires drift during Gen2 migration drift detection.

An AppSync ApiKey Expires value is set to createTime + validity at deploy time, and then re-derived at a later lock time when drift is computed. Because the two epoch timestamps are computed at different moments, they legitimately differ, so CloudFormation reports a drift that is not a real configuration change. A real observed pair from the migration e2e runs was Expected 1791274802 vs Deployed 1.7912736E+9 (a benign delta of roughly 20 minutes; note the deployed value also comes back in scientific notation).

The new isAppSyncApiKeyExpiresTimeRelativeDrift filter drops this specific case. It is guarded so it only ever fires on AWS::AppSync::ApiKey resources, only on the /Expires property path, and only when both the expected and actual values parse as epoch-like numbers (finite and greater than roughly the year 2020). Those guards mean the filter cannot mask a non-timestamp mutation or any change to a different property.

Why this is not a source regression

The drift-detection code is unchanged between July and now. This surfaced because CloudFormation's drift output began reporting the time-relative /Expires difference, not because any code changed.

Impact

Clears the 7 gen2_migration e2e groups that were failing on /Expires drift.

Testing

packages/amplify-cli drift unit tests pass 12/12, including four new cases covering the real CI pair, a plain-integer epoch pair, non-epoch and non-numeric values (not filtered), and wrong resource type / wrong property path (not filtered).