fallback for truncated ListObjects V1 responses without NextMarker

[387809109]

Description of Changes

For non-AWS endpoints, netCDF-Java 5.9.1 selected ListObjects V1.

The original pagination logic was:

String continuationToken =
    useV2
        ? responseV2.nextContinuationToken()
        : responseV1.nextMarker();
updateObjectList(continuationToken);

A direct AWS SDK ListObjects V1 request for Swift returned:

count=1000
isTruncated=true
nextMarker=null

The page was valid and truncated, but Swift did not return NextMarker, therefore netCDF-Java repeatedly requested the first page.

changed that part to add a fallback for truncated ListObjects V1 responses without NextMarker

PR Checklist

• Link to any issues that the PR addresses
• Add labels
• Open as a draft PR
  until ready for review
• Make sure GitHub tests pass
• Mark PR as "Ready for Review"

[CLAassistant]

All committers have signed the CLA.

[lesserwhirls]

Thank you for your contribution! This looks ready to go from my end. Once you mark it as ready for review I will happily merge this fix.