test(storage): mitigate integration test flakiness

[coryan]

Reduce the number of buckets created by the integration tests, and be a little more patient during bucket creation.

Part of the work for #3567

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.74%. Comparing base (bd3452e) to head (6dc3645).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3571      +/-   ##
==========================================
+ Coverage   95.72%   95.74%   +0.02%     
==========================================
  Files         124      124              
  Lines        4979     4979              
==========================================
+ Hits         4766     4767       +1     
+ Misses        213      212       -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.