MAGETWO-62975: [FT] Functional test Magento\Customer\Test\TestCase\RegisterCustomerFrontendEntityTest is failed

--remove test from unstable

Author: Sergii Kovalenko

dev/tests/functional/tests/app/Magento/Customer/Test/TestCase/RegisterCustomerFrontendEntityTest.xml

@@ -32,7 +32,7 @@
             <constraint name="Magento\Newsletter\Test\Constraint\AssertCustomerIsSubscribedToNewsletter" />
         </variation>
         <variation name="RegisterCustomerFrontendEntityTestVariation3" summary="Register Customer" ticketId="MAGETWO-12394">
-            <data name="tag" xsi:type="string">test_type:acceptance_test, test_type:extended_acceptance_test, stable:no</data>
+            <data name="tag" xsi:type="string">test_type:acceptance_test, test_type:extended_acceptance_test</data>
             <data name="customer/data/firstname" xsi:type="string">john</data>
             <data name="customer/data/lastname" xsi:type="string">doe</data>
             <data name="customer/data/email" xsi:type="string">johndoe%isolation%@example.com</data>