Analyst sees when a GTFS-RT feed is broken

[ohrite]

User story / feature request

When a GTFS-RT feed has < x% GTFS-RT Vehicle Position Completeness, an Analyst only sees a subset of results (i.e. every first block).

Related: MobilityData/gtfs-realtime-validator#159

Acceptance Criteria

Please enter something that can be verified to show that this user story is satisfied. For example: I can join table X with table Y. or Column A appears in table Z in Metabase.

Notes

Please enter any additional information that will facilitate the completion of this ticket. For example: Are there any constraints not mentioned above? Are there any alternatives you have considered?