Test to ensure IndexingService can't start w/ mismatching index provider

An IndexingService is started with a SchemaIndexProviderMap that can
resolve a SchemaIndexProvider given a key/version. If initIndexes is
called with an index rule that cannot be resolved (which would translate
to: "Your db has been using provider X for an index and now it's no longer
available") it should fail, and in the extension the database startup will
fail. This was already the case so this just adds a clear test case for it.