🐛 Ensure solr adapter on account switch

This commit will ensure that the adapter is set to solr.  There seems to
be an error occuring when the worker is switching accounts where it
loses the adapter and raises an error.

app/models/solr_endpoint.rb

@@ -41,6 +41,8 @@ def connection_options
     #
     # https://github.com/samvera/hyrax/blob/a5a0ae9e56df857a92fc53ae86216cbb007db47a/lib/valkyrie/indexing/solr/indexing_adapter.rb#L83-L101
     base_options['core'] ||= switchable_options['collection']
+    # Ensure we have the solr adapter set
+    base_options['adapter'] ||= 'solr'
 
     # NOTE: the switchable_options includes two keys: "collection" and "url"
     #       The "url" should be used to make the connection to Solr.