Fix cloud cover requirements

[jhkennedy]

Currently, our most common error is a missing eo:cloud_cover property in the STAC item.

From close inspection, it looks like we should be using landsat:cloud_cover_land:

• This matches what ITS_LIVE was doing previously better: https://github.com/nasa-jpl/its_live_production/blob/main/src/tools/missingpairstools/find_all_USGS_Collection2_imagepairs_for_jsoncatalogs.py#L266
• eo:cloud_cover appears to be missing for items where the cloud % was not calculated (CLOUD_COVER = -1 in the product metadata), but the corrosponding landsat:cloud_cover_land does appear to exists with a value of -1 in these cases.

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TODOs:

• determine how to handle scenes when cloud cover was not calculated (value of -1). Previously, the scenes would be used as there is only a simple <= comparison being used and the -1 values aren't handled specially:
  https://github.com/nasa-jpl/its_live_production/blob/main/src/tools/missingpairstools/find_all_USGS_Collection2_imagepairs_for_jsoncatalogs.py#L266