tabledesc,descs: ensure to propagate IsUncommittedVersion when hydrating

When we hydrate a table descriptor which has been modified during the
transaction we want to ensure that we propagate the information that
indicates that it has been modified.

Release justification: Part of a larger fix to a major performance
enhancement for user-defined types, a new feature in this release.

Release note: None

pkg/sql/catalog/descs/collection.go

@@ -1110,13 +1110,12 @@ func (tc *Collection) hydrateTypesInTableDesc(
 			// Proceed to hydrating a fresh copy.
 		}
 
-		// TODO(ajwerner): Propagate the IsModified status here.
 		// Make a copy of the underlying descriptor before hydration.
 		descBase := protoutil.Clone(t.TableDesc()).(*descpb.TableDescriptor)
 		if err := typedesc.HydrateTypesInTableDescriptor(ctx, descBase, getType); err != nil {
 			return nil, err
 		}
-		return tabledesc.NewImmutable(*descBase), nil
+		return tabledesc.NewImmutableWithIsUncommittedVersion(*descBase, t.IsUncommittedVersion()), nil
 	default:
 		return desc, nil
 	}

pkg/sql/catalog/tabledesc/structured.go

@@ -187,8 +187,21 @@ func MakeImmutable(tbl descpb.TableDescriptor) Immutable {
 }
 
 // NewImmutable returns a Immutable from the given TableDescriptor.
+// This function assumes that this descriptor has not been modified from the
+// version stored in the key-value store.
 func NewImmutable(tbl descpb.TableDescriptor) *Immutable {
+	return NewImmutableWithIsUncommittedVersion(tbl, false /* isUncommittedVersion */)
+}
+
+// NewImmutableWithIsUncommittedVersion returns a Immutable from the given
+// TableDescriptor and allows the caller to mark the table as corresponding to
+// an uncommitted version. This should be used when constructing a new copy of
+// an Immutable from an existing descriptor which may have a new version.
+func NewImmutableWithIsUncommittedVersion(
+	tbl descpb.TableDescriptor, isUncommittedVersion bool,
+) *Immutable {
 	desc := MakeImmutable(tbl)
+	desc.isUncommittedVersion = isUncommittedVersion
 	return &desc
 }