Fix WAV resources ignoring the AudioServer's 'global_rate_scale' value

(cherry picked from commit 04ebe4e7a4e6746d7ca586c2243580ee12bbd245)

scene/resources/audio_stream_sample.cpp

@@ -254,7 +254,8 @@ void AudioStreamPlaybackSample::mix(AudioFrame *p_buffer, float p_rate_scale, in
 		sign = -1;
 	}
 
-	float base_rate = AudioServer::get_singleton()->get_mix_rate();
+	float global_rate_scale = AudioServer::get_singleton()->get_global_rate_scale();
+	float base_rate = AudioServer::get_singleton()->get_mix_rate() * global_rate_scale;
 	float srate = base->mix_rate;
 	srate *= p_rate_scale;
 	float fincrement = srate / base_rate;