ENH: apply paging such that no unwanted jobs are being triggered

Summary

Performance was bad because a paged retrieve would also load and execute jobs for entities which are not on the requested page.

Focus

Two things happened:

1. There was a trivial but wrong implementation of Entity#skipJob(). Jobs would never be skipped, even if an entity had entity status IGNORE. This was a one-liner.
2. Because the paging was being applied after the query (and other jobs) some (and possibly A LOT) entity jobs would be added to the schedule which are not necessary because the entities are not the requested page. This is the rest of the changes.

Test Environment

Unit test should be sufficient.

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• All automated tests pass
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src/main/java/org/caosdb/server/jobs/core/ExecuteQuery.java

@@ -59,18 +59,18 @@ public class ExecuteQuery extends FlagJob {
       }
       getContainer().addMessage(queryInstance);
 
-      int index = 0;
-      int length = getContainer().size();
+      int startIndex = 0;
+      int endIndex = getContainer().size();
 
       if (((Retrieve) getTransaction()).hasPaging()) {
         Retrieve.Paging paging = ((Retrieve) getTransaction()).getPaging();
-        index = Math.min(getContainer().size(), paging.index);
-        length = Math.min(getContainer().size(), paging.length);
+        startIndex = Math.min(getContainer().size(), paging.startIndex);
+        endIndex = Math.min(getContainer().size(), paging.endIndex);
       }
 
       int ii = 0;
       for (final EntityInterface entity : getContainer()) {
-        if (ii >= index && ii < length) {
+        if (ii >= startIndex && ii < endIndex) {
           getTransaction().getSchedule().addAll(loadJobs(entity, getTransaction()));
         } else {
           entity.setEntityStatus(EntityStatus.IGNORE);