Retrieve hover over info from models rather than MAST

[stscijgbot-jwql]

Issue JWQL-190 was created on JIRA by Bryan Hilbert:

Information that is displayed in the thumbnail hover over is currently retrieved via a MAST query ([https://github.com/spacetelescope/jwql/blob/develop/jwql/website/apps/jwql/data_containers.py#L2028)] It might improve performance if we instead get this information from the Django models.