Constants should always be only assigned once. The logical OR assignment
of a constant is a relic of the past before we used zeitwerk for
autoloading and had bugs where a file could be loaded twice resulting in
constant redefinition warnings.
Since we just released 3.2, this is a good time to drop deprecated columns. This is a two-phase process. First we drop the columns, then we remove the ignored_columns declarations. Because of that I'm batching all deprecated columns for dropping here first. Once a full deploy is done we remove the declarations.