Ignore repair_run_by_cluster_v2 rows with no corresponding repair (#1478

)

* Ignore repair_run_by_cluster_v2 rows with no corresponding repair
When bad things (like Reaper filling the drive with logs) happen,
it's possible to end up with repair_run_by_cluster_v2 rows with no
corresponding repair row, which breaks Reaper.  So, just skip them.

* Cleaner version of omitting missing repair_run rows
Per comment, rewrite to stick a filter between instead
of shoving a ternary into the map.  Cleaner and easier to read.

src/server/src/main/java/io/cassandrareaper/storage/repairrun/CassandraRepairRunDao.java

@@ -30,6 +30,7 @@
 import java.util.Collection;
 import java.util.Date;
 import java.util.List;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import java.util.SortedSet;
@@ -395,15 +396,14 @@ public List<RepairRun> getRepairRunsForClusterPrioritiseRunning(String clusterNa
                 )
         )
     );
+
     // Defuture the repair_run rows and build the strongly typed RepairRun objects from the contents.
     return repairRunFutures
         .stream()
-        .map(
-            row -> {
-              Row extractedRow = row.getUninterruptibly().one();
-              return buildRepairRunFromRow(extractedRow, extractedRow.getUUID("id"));
-            }
-        ).collect(Collectors.toList());
+        .map(row -> row.getUninterruptibly().one())
+        .filter(Objects::nonNull)
+        .map(extractedRow -> buildRepairRunFromRow(extractedRow, extractedRow.getUUID("id")))
+        .collect(Collectors.toList());
   }
 
   @Override