Search: exclude platforms that have been removed from code but exist in db/elasticsearch.
Search: exclude platforms that have been removed from code but exist in db/elasticsearch.

Fixes https://app.bugsnag.com/tidelift/libraries-dot-io/errors/60ae50aca940100007305441

librariesio/libraries.io,librariesio/libraries.io,librariesio/libraries.io,librariesio/libraries.io