[#25745] YSQL: Fix YsqlMajorUpgradeDdlBlockingTest.TestDdlsDuringUpgrade

Summary:
Test failure was due to f976939/D41420, since we now get a different error message based on the state of the cleanup.

Fixes #25745
Jira: DB-15026

Test Plan: YsqlMajorUpgradeDdlBlockingTest.TestDdlsDuringUpgrade

Reviewers: telgersma

Reviewed By: telgersma

Subscribers: sergei, ybase

Differential Revision: https://phorge.dev.yugabyte.com/D41473

src/yb/integration-tests/upgrade-tests/ysql_major_upgrade_ddl_blocking-test.cc

@@ -60,10 +60,19 @@ class YsqlMajorUpgradeDdlBlockingTest : public Pg15UpgradeTestBase {
       if (!error_expected) {
         RETURN_NOT_OK(status);
       } else {
-        SCHECK(
-            !status.ok() &&
-                status.message().ToString().find(kExpectedDdlError) != std::string::npos,
-            IllegalState, "Unexpected status: ", status.ToString());
+        if (upgrade_state_ == UpgradeState::kAfterUpgrade) {
+          // Depending on the cleanup state we may get different errors after the upgrade.
+          SCHECK(
+              !status.ok() &&
+                  (status.message().ToString().find(kExpectedDdlError) != std::string::npos ||
+                   status.message().ToString().find("unknown_table_name") != std::string::npos),
+              IllegalState, "Unexpected status: ", status.ToString());
+        } else {
+          SCHECK(
+              !status.ok() &&
+                  status.message().ToString().find(kExpectedDdlError) != std::string::npos,
+              IllegalState, "Unexpected status: ", status.ToString());
+        }
       }
     }
     return Status::OK();