[audio_core] fix OOB copy when silencing channel on shutdown (#3969)

when shutting down the emulator will silence any remaining audio from the output buffer
however this is for some reason stored in an array instead of being a simple memset
additionally, said array can be small enough (`frame_size_bytes > silence.size()`) to cause a funky noise to play at the end

Signed-off-by: lizzie <lizzie@eden-emu.dev>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3969
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: crueter <crueter@eden-emu.dev>

src/audio_core/sink/sink_stream.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
@@ -177,10 +177,8 @@ void SinkStream::ProcessAudioOutAndRender(std::span<s16> output_buffer, std::siz
             queued_buffers.store(0);
             release_cv.notify_one();
         }
-
-        static constexpr std::array<s16, 6> silence{};
         for (size_t i = 0; i < num_frames; i++)
-            std::memcpy(&output_buffer[i * frame_size], silence.data(), frame_size_bytes);
+            std::memset(&output_buffer[i * frame_size], 0, frame_size_bytes);
         return;
     }