Remove QUIC_EXPORT_PRIVATE from QuicBufferedPacketStore
Remove QUIC_EXPORT_PRIVATE from QuicBufferedPacketStore

This will allow us to move QuicBufferedPacketStore
out of Chrome /net and into test tools.

gfe-relnote: n/a, Chrome-only change
PiperOrigin-RevId: 308749816
Change-Id: I94cdcc8742da59438c6a3269d490c69f6db32623

google/quiche,google/quiche,google/quiche,google/quiche