Revert "added a new warning for files with missing columns, to be handled during file processing"

This reverts commit bd3c1d0.

Author: nalduu

data/migrate/Errors-Backfilling.csv

@@ -73,8 +73,6 @@ Error Code,Error Type,Message Template,Notes
 249,Warning,#TIMESTAMP table after #{table} is missing\, deriving based on requirements,Reserved for Umkehr data tables
 250,Warning,Excess field {field} does not belong in table {table}
 251,Warning,Duplicate observations found in #{table} for Date={date},Reserved for Umkehr data tables
-252,Error,Trailing commas found in #{table} header
-253,Warning,Number of columns in {table} content row does not match with the number of column headers
 301,Warning,Failed to parse #{table}.Time {component}: contains invalid characters
 302,Warning,Failed to parse #{table}.Date {component}: contains invalid characters
 303,Warning,#{table}.Date {component} is not within allowable range [{lower}]-[{upper}],Reserved for year and month components