Rename PacketBuffer tests to follow conventions

Rename file with tests to match code under test.
Rename fixture by moving 'Test' from prefix to suffix

Bug: None
Change-Id: I54c36d3b517bde7cdffa3a7e74528cc464ea7ad7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/157301
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29532}
diff --git a/modules/video_coding/BUILD.gn b/modules/video_coding/BUILD.gn
index 2bbc930..924e2fa 100644
--- a/modules/video_coding/BUILD.gn
+++ b/modules/video_coding/BUILD.gn
@@ -836,6 +836,7 @@
       "jitter_estimator_tests.cc",
       "loss_notification_controller_unittest.cc",
       "nack_module_unittest.cc",
+      "packet_buffer_unittest.cc",
       "receiver_unittest.cc",
       "rtp_frame_reference_finder_unittest.cc",
       "session_info_unittest.cc",
@@ -850,7 +851,6 @@
       "utility/quality_scaler_unittest.cc",
       "utility/simulcast_rate_allocator_unittest.cc",
       "video_codec_initializer_unittest.cc",
-      "video_packet_buffer_unittest.cc",
       "video_receiver_unittest.cc",
     ]
     if (rtc_use_h264) {