namespace-concat in fbcode/quic

Summary:
Concatenate adjacent namespaces + format

This is a codemod. It was automatically generated and will be landed once it is approved and tests are passing in sandcastle.
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Autodiff project: nc
Autodiff partition: fbcode.quic
Autodiff bookmark: ad.nc.fbcode.quic

Reviewed By: hanidamlaj

Differential Revision: D65365244

fbshipit-source-id: 0bbaa7684d03caf8fc8eff3439a0865940398220

quic/api/test/QuicBatchWriterTest.cpp

@@ -18,8 +18,7 @@
 
 using namespace testing;
 
-namespace quic {
-namespace testing {
+namespace quic::testing {
 
 constexpr const auto kStrLen = 10;
 constexpr const auto kStrLenGT = 20;
@@ -864,5 +863,4 @@ TEST_F(SinglePacketBackpressureBatchWriterTest, TestFailedWriteCachedOnEAGAIN) {
   EXPECT_FALSE(conn_.pendingWriteBatch_.buf);
 }
 
-} // namespace testing
-} // namespace quic
+} // namespace quic::testing