[#15026] Minor refactoring of xcluster consistency computation

Summary:
Using a single line statement when computing use_xcluster_database_consistency.
Replacing ASSERT_RESULT with ASSERT_OK in xcluster_safe_time-itest as result output is not read.

Test Plan: xcluster_safe_time-itest

Reviewers: rahuldesirazu, slingam, dmitry

Reviewed By: dmitry

Subscribers: ybase

Differential Revision: https://phabricator.dev.yugabyte.com/D21130

ent/src/yb/integration-tests/xcluster_safe_time-itest.cc

@@ -735,17 +735,15 @@ TEST_F_EX(XClusterConsistencyTest, LoginWithNoSafeTime, XClusterConsistencyNoSaf
   // Verify that we can login and query a catalog table.
   auto conn = ASSERT_RESULT(consumer_cluster_.ConnectToDB(
       consumer_table1_->name().namespace_name(), true /*simple_query_protocol*/));
-
-  auto result = ASSERT_RESULT(conn.Fetch("SELECT relname FROM pg_catalog.pg_class LIMIT 1;"));
+  ASSERT_OK(conn.Fetch("SELECT relname FROM pg_catalog.pg_class LIMIT 1"));
 
   // Verify that we can't read user table with default consistency.
   const auto query = Format("SELECT * FROM $0", GetCompleteTableName(consumer_table1_->name()));
-
   ASSERT_NOK(conn.Execute(query));
 
-  // Verify that we can't read user table with tablet level consistency.
+  // Verify that we can read user table with tablet level consistency.
   ASSERT_OK(conn.Execute("SET yb_xcluster_consistency_level = tablet"));
-  result = ASSERT_RESULT(conn.Fetch(query));
+  ASSERT_OK(conn.Fetch(query));
 }
 
 }  // namespace enterprise

src/yb/yql/pggate/pg_session.cc

@@ -538,13 +538,9 @@ Result<PerformFuture> PgSession::Perform(
   }
   options.set_force_global_transaction(global_transaction);
 
-  auto use_xcluster_database_consistency =
-      yb_xcluster_consistency_level == XCLUSTER_CONSISTENCY_DATABASE;
-  if (use_catalog_session || pg_txn_manager_->IsDdlMode()) {
-    // For Catalog sessions and DDLs we always want to read our universe's latest data.
-    use_xcluster_database_consistency = false;
-  }
-  options.set_use_xcluster_database_consistency(use_xcluster_database_consistency);
+  options.set_use_xcluster_database_consistency(
+      yb_xcluster_consistency_level == XCLUSTER_CONSISTENCY_DATABASE &&
+      !(use_catalog_session || pg_txn_manager_->IsDdlMode()));
 
   auto promise = std::make_shared<std::promise<PerformResult>>();