changes in metadata from NSIDC cause icepyx failures

[JessicaS11]

In addition to the current integration test failure, changes to the ICESat-2 metadata are currently causing icepyx to be unable to query ATL06. A request to: https://cmr.earthdata.nasa.gov/search/collections.json?short_name=ATL06
returns:

feed
updated	"2025-10-28T18:01:59.369Z"
id	"https://cmr.earthdata.nasa.gov:443/search/collections.json?short_name=ATL06"
title	"ECHO dataset metadata"
entry	[]

feed updated "2025-10-28T18:01:59.369Z" id "[https://cmr.earthdata.nasa.gov:443/search/collections.json?short_name=ATL06](https://cmr.earthdata.nasa.gov/search/collections.json?short_name=ATL06)" title "ECHO dataset metadata" entry []

where entry should contain all the ATL06 metadata.

We have no control over the metadata (but it is always appreciated when we report them to NSIDC), but we can check and surface errors/missing metadata early on when it happens rather than waiting for an error/failure later in the code when we try to use that information.

[JessicaS11]

Thanks to @asteiker for confirming there is a known issue with CMR currently. CC: @mikala-nsidc