Fix integer casting bug

[avaleske]

At

bloom/backend/core/src/shared/filter/custom_filters.ts

Line 35 in d7ac378

const hasAvailabilityColumnName = `LOWER(CAST(${filterTypeToFieldMap[filterType]} as text))`

it looks like we're casting an integer field to be a text field, and then doing an >= comparison on it.

We should fix this, so we do a numerical comparison instead of a lexicographic comparison.