Fix missing AuthContext on New Partition (#4550)

Co-authored-by: Ryan Caudy <ryan@deephaven.io>

engine/table/src/main/java/io/deephaven/engine/table/impl/sources/UnionSourceManager.java

@@ -4,6 +4,7 @@
 package io.deephaven.engine.table.impl.sources;
 
 import io.deephaven.base.verify.Assert;
+import io.deephaven.engine.context.ExecutionContext;
 import io.deephaven.engine.rowset.*;
 import io.deephaven.engine.rowset.RowSetFactory;
 import io.deephaven.engine.table.*;
@@ -61,6 +62,7 @@ public class UnionSourceManager {
  private final MergedListener mergedListener;
  private final ConstituentChangesListenerRecorder constituentChangesListener;
  private final UpdateCommitter<UnionSourceManager> updateCommitter;
+ private final ExecutionContext executionContext;
 
  public UnionSourceManager(@NotNull final PartitionedTable partitionedTable) {
  constituentChangesPermitted = partitionedTable.constituentChangesPermitted();
@@ -99,11 +101,17 @@ public UnionSourceManager(@NotNull final PartitionedTable partitionedTable) {
 
  updateCommitter = new UpdateCommitter<>(this, partitionedTable.table().getUpdateGraph(),
  usm -> usm.unionRedirection.copyCurrToPrev());
+
+ executionContext = ExecutionContext.newBuilder()
+ .markSystemic()
+ .captureUpdateGraph()
+ .build();
  } else {
  listenerRecorders = null;
  mergedListener = null;
  constituentChangesListener = null;
  updateCommitter = null;
+ executionContext = null;
  }
 
  try (final Stream<Table> initialConstituents = currConstituents()) {
@@ -244,7 +252,8 @@ private MergedUnionListener(
  protected void process() {
  final TableUpdate constituentChanges = getAndCheckConstituentChanges();
  final TableUpdate downstream;
- try (final ChangeProcessingContext context = new ChangeProcessingContext(constituentChanges)) {
+ try (final SafeCloseable ignored = executionContext.open();
+ final ChangeProcessingContext context = new ChangeProcessingContext(constituentChanges)) {
  downstream = context.processChanges();
  } catch (Throwable ex) {
  propagateError(false, ex, entry);