Revert Relaxed singleton in RemoteFunctionTest causing SEGFAULT

The SingletonVault::Type::Relaxed change was causing a SEGFAULT
in the adapters CI build (Release + shared + mono_library). The test
passes on main without this change. The singleton registration warning
is non-fatal and does not need to be suppressed.

Author: kgpai

velox/functions/remote/client/tests/RemoteFunctionTest.cpp

@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-#include <folly/Singleton.h>
 #include <folly/SocketAddress.h>
 #include <folly/init/Init.h>
 #include <gmock/gmock.h>
@@ -406,12 +405,6 @@ VELOX_INSTANTIATE_TEST_SUITE_P(
 
 int main(int argc, char** argv) {
   testing::InitGoogleTest(&argc, argv);
-  // Use Relaxed mode to allow singleton registration after
-  // registrationComplete() which is needed when building with shared
-  // libraries (-DVELOX_BUILD_SHARED=ON) since fbthrift singletons are
-  // registered when the shared library is loaded.
-  folly::SingletonVault::singleton()->setType(
-      folly::SingletonVault::Type::Relaxed);
   folly::Init init{&argc, &argv, false};
   return RUN_ALL_TESTS();
 }