Delete method NetEqImpl::CurrentDelayMs, used only by tests

Bug: None
Change-Id: If94695f60ed804f6b43be828dd93f02826269140
Reviewed-on: https://webrtc-review.googlesource.com/c/116687
Reviewed-by: Ivo Creusen <ivoc@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26193}

modules/audio_coding/neteq/neteq_unittest.cc

@@ -404,10 +404,6 @@ void NetEqDecodingTest::DecodeAndCompare(
       ASSERT_EQ(0, neteq_->NetworkStatistics(&current_network_stats));
       ASSERT_NO_FATAL_FAILURE(network_stats.AddResult(current_network_stats));
 
-      // Compare with CurrentDelay, which should be identical.
-      EXPECT_EQ(current_network_stats.current_buffer_size_ms,
-                neteq_->CurrentDelayMs());
-
       // Verify that liftime stats and network stats report similar loss
       // concealment rates.
       auto lifetime_stats = neteq_->GetLifetimeStatistics();