Fix russian translation for first and last page links in pager

Resources/translations/SonataAdminBundle.ru.xliff

@@ -92,11 +92,11 @@
             </trans-unit>
             <trans-unit id="link_first_pager">
                 <source>link_first_pager</source>
-                <target>link_first_pager</target>
+                <target>Первая</target>
             </trans-unit>
             <trans-unit id="link_last_pager">
                 <source>link_last_pager</source>
-                <target>link_last_pager</target>
+                <target>Последняя</target>
             </trans-unit>
             <trans-unit id="Admin">
                 <source>Admin</source>