Remove entrypoint from SOLR Tugboat image

Tugboat requires the entrypoint to remain the same so they can run their
init and build steps as per https://docs.tugboatqa.com/reference/tugboat-images/#solr

We must leave the custom image since we need the solr config.

tugboat-solr/Dockerfile

@@ -3,5 +3,3 @@ ARG VERSION=latest
 FROM tugboatqa/solr:$VERSION
 
 ADD config /solr-conf/conf
-
-ENTRYPOINT ["solr-precreate", "drupal", "/solr-conf"]