[integ-test] Make get-cluster/image-log-events integ tests robust to empty pages

[hanwen-cluster]

Description of changes

GetLogEvents may return partially full or empty pages even when more events are available; limit is only an upper bound. The previous checks assumed limit=1 always returned exactly one event and indexed events[0], making them flaky.

Replace the filter matrix with a full pagination of the log stream (until the returned token equals the one passed in) and assert the stream is not empty. Arguments like limit are already covered by unit tests, and don't have to be in integration tests.

Tests

• Ongoing

References

• Link to impacted open issues.
• Link to related PRs in other packages (i.e. cookbook, node).
• Link to documentation useful to understand the changes.

Checklist

• Make sure you are pointing to the right branch.
• If you're creating a patch for a branch other than develop add the branch name as prefix in the PR title (e.g. [release-3.6]).
• Check all commits' messages are clear, describing what and why vs how.
• Make sure to have added unit tests or integration tests to cover the new/modified code.
• Check if documentation is impacted by this change.

Please review the guidelines for contributing and Pull Request Instructions.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.