fix: make retry examples using seeded random

[vip-amzn]

Issue #, if available:
closes #93
Changes:

1. step_with_retry.py:
   With counter-based deterministic behavior:

   • Attempt 1: counter = 1 < 2 → raises RuntimeError ❌
   • Attempt 2: counter = 2 >= 2 → succeeds ✓

2. steps_with_retry.py:
   With counter-based deterministic behavior:

   • Poll 1, Attempt 1: counter = 1 → raises RuntimeError ❌
   • Poll 1, Attempt 2: counter = 2 → returns None
   • Poll 2, Attempt 1: counter = 3 → returns item ✓

Dependencies

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[wangyb-A]

Is it possible to pass the random seed through lambda invoke event? So that we can have same random seed in both lambda function and the pytest function. It keeps the randomness and make it easier to assert on the random result.

stale