storage: add retries to bucket metadata updates in integration tests
storage: add retries to bucket metadata updates in integration tests

This introduces a retry to account for propagation delay in
metadata update that has been causing flakes.
Create functions that attempts to retry for up to 11s and use it to
wrap the functions that call the API.

Fixes #1699

Change-Id: I3169674376cded2afbd53091eca757aba166c285
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/49872
Reviewed-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Chris Cotter <b879ae7d4b52f11ce9f60d9854075eb8eebaf7a9@google.com>

googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go