Update TransformSurvivesUpgradeIT.java

Author: davidkyle

x-pack/qa/rolling-upgrade/src/test/java/org/elasticsearch/upgrades/TransformSurvivesUpgradeIT.java

@@ -95,8 +95,7 @@ public void testTransformRollingUpgrade() throws Exception {
                 if (Booleans.parseBoolean(System.getProperty("tests.first_round")) == false) {
                     lastCheckpoint = 2;
                 }
-                verifyContinuousTransformHandlesData(lastCheckpoint);
-                verifyUpgradeFailsIfMixedCluster();
+                verifyContinuousTransformHandlesData(lastCheckpoint);                
             }
             case UPGRADED -> {
                 client().performRequest(waitForYellow);
@@ -232,19 +231,6 @@ private void verifyContinuousTransformHandlesData(long expectedLastCheckpoint) t
         });
     }
 
-    private void verifyUpgradeFailsIfMixedCluster() {
-        // upgrade tests by design are also executed with the same version, this check must be skipped in this case, see gh#39102.
-        if (isOriginalClusterCurrent()) {
-            return;
-        }
-        var oldestVersion = Version.fromString(UPGRADE_FROM_VERSION);
-        if (oldestVersion.onOrAfter(Version.V_9_3_0)) {
-            final Request upgradeTransformRequest = new Request("POST", getTransformEndpoint() + "_upgrade");
-            Exception ex = expectThrows(Exception.class, () -> client().performRequest(upgradeTransformRequest));
-            assertThat(ex.getMessage(), containsString("Cannot upgrade transforms while cluster upgrade is in progress"));
-        }
-    }
-
     private void verifyUpgrade() throws IOException {
         final Request upgradeTransformRequest = new Request("POST", getTransformEndpoint() + "_upgrade");
         Response response = client().performRequest(upgradeTransformRequest);