ACQE-6375: Registered Checkout Using PayPal Smart Button and Flat Rate

Added pr_exclude tag for 3rd party testcase

Author: shefalijain-22

app/code/Magento/Paypal/Test/Mftf/Test/RegisteredPaypalCheckoutWithFlatRatePaymentActionSaleTest.xml

@@ -16,7 +16,7 @@
             <severity value="CRITICAL"/>
             <testCaseId value="AC-5037"/>
             <group value="3rd_party_integration"/>
-            <!-- <group value="pr_exclude"/>-->
+            <group value="pr_exclude"/>
         </annotations>
         <before>
             <actionGroup ref="AdminLoginActionGroup" stepKey="login"/>