Update to 8.18.1 and get rid of k8s entrypoint

Author: simonwoerpel

Dockerfile

@@ -1,11 +1,7 @@
-FROM elasticsearch:7.16.1
+FROM elasticsearch:8.18.1
 LABEL org.opencontainers.image.source = "https://github.com/openaleph/aleph-elasticsearch"
 
 RUN bin/elasticsearch-plugin install --batch repository-s3 \
-    && bin/elasticsearch-plugin install --batch repository-gcs \
     && bin/elasticsearch-plugin install --batch analysis-icu
 
-COPY k8s-entrypoint.sh /k8s-entrypoint.sh
 COPY --chown=elasticsearch synonames.txt /usr/share/elasticsearch/config/
-
-ENTRYPOINT [ "/k8s-entrypoint.sh" ]