Export reservedstate.service to serverless (#1956)

Author: tvernum

server/src/main/java/module-info.java

@@ -316,7 +316,7 @@
     exports org.elasticsearch.repositories.blobstore;
     exports org.elasticsearch.repositories.fs;
     exports org.elasticsearch.reservedstate;
-    exports org.elasticsearch.reservedstate.service to org.elasticsearch.multiproject;
+    exports org.elasticsearch.reservedstate.service to org.elasticsearch.multiproject, org.elasticsearch.serverless.multiproject;
     exports org.elasticsearch.rest;
     exports org.elasticsearch.rest.action;
     exports org.elasticsearch.rest.action.admin.cluster;