Excluded None fields from ReingestGroup JSON

.../pexable/ingest_envoy/ingest_envoy/manifest_components.py

...t_envoy/test/examples/full_curation_evla_eb_manifest.json

...nvoy/test/examples/full_curation_evla_image_manifest.json

...nvoy/test/examples/partial_curation_evla_eb_manifest.json

...partial_curation_evla_eb_manifest_no_curation_source.json

...tables/pexable/ingest_envoy/test/test_curator_manifest.py