Consistently interning the NodePublic's throughout DERP, particularly
inside the maps reduces memory usage and reduces lookup costs in the
associated data structures.
It is not clear exactly how efficient the weak pointers will be in
practice, but estimating this using derpstress with 10k conns pushing
40kpps in each direction, this is patch grows heap at approximately half
the rate vs. the old code and has fewer instances of long stalls that
trigger i/o timeouts for the clients.
Updates tailscale/corp#24485
Signed-off-by: James Tucker <james@tailscale.com>
f7ad04bea4