This should resolve when dual stack is fully implemented (#6472). Until then, a partial implementation should be possible without requiring much throwaway work.

• Create a reproduction test case for this scenario and confirm that load is not reported correctly.
• Change pick_first to have one subchannel per address. Probably skip implementing happy eyeballs for now.
• Set an attribute on every subchannel creation operation (for outlier detection to read).
• Disable outlier detection if pick_first is used (detected via address attribute). (See C++ version of this change here: [outlier detection] hack to prevent OD from working with pick_first grpc#33336)

That should be all we need to correct this issue.