Explore running validation on feeds with unknown_column notices

[emmambd]

Describe the problem

Investigation in #1767 showed that Flex feeds are not being parsed because they have the unknown_column notice. We want to be confident that this is the reason why Flex feeds are having parsing issues.

Proposed solution

• Run analysis to see how many feeds in the acceptance tests have the unknown column notice (can use the Raw Data from the last analysis)

Alternatives you've considered

No response

Additional context

No response

[jcpitre]

Tasks:

• Investigate why unknown column leads to unparsable
• Test by adding a column to a feed without errors and see what happens

[qcdyx]

1. It's the missing_required_field 'stop_id' that leads to a validation error, which makes stop_times.txt have a status of UNPARSABLE_ROWS.
2. added a 'UNKNOWN_COLUMN' to stop_times.txt of browncounty-mn-us--flex-v2 dataset, run GTFS validator, no UNPARSABLE_ROWS for stop_times.txt.

[emmambd]

Closing this issue as a duplicate of #1767