Instead of storing GeoJSON for <mapframe> tags in the
page_props table parser cache, we should store it in a table that's really just a key-value store, where the keys are the hashes and the values are the GeoJSON blobs. This is basically solution #1 from T119043: Graph/Graphoid/Kartographer - data storage architecture but without the second rev tracking table.
We would need to modify the code that writes the GeoJSON blobs
to page_props (indirectly through ParserOutput methods) to instead write to this new table, and modify the api.php module to read from this new table instead of page_props. We'd also need a migration script (or have the API module read from both).