Fix semver hazard in S3 stalled stream protection test (#3541)

Merging #3485 uncovered a semver hazard in the S3 stalled stream
protection test due to a subtle (but intentional) change in grace period
behavior for stalled streams. That semver hazard was going to cause the
SDK release to fail, so #3485 was reverted, and this PR modifies the
test so that it will pass with both versions of stalled stream
protection as a temporary measure. Once this PR is merged and released,
then the new stalled stream protection can be merged again.

I tested this by updating the runtime-versioner in #3540 so that I could
patch the currently released SDK with these test changes in place, with
a local copy of smithy-rs that has the new stalled stream protection
implementation. I ran all the tests across all the services in this
configuration to verify this was the only hazard that will be hit.

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